Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 179 PQILSQPHNIWNVTGQDVIFGCEVFAYPMASIEWRKDGLDIQlpgDDPHISVQFRGGPQKFEvtgwlqIQALRPSDEGTY 258
Cdd:pfam07679   1 PKFTQKPKDVEVQEGESARFTCTVTGTPDPEVSWFKDGQPLR---SSDRFKVTYEGGTYTLT------ISNVQPDDSGKY 71

                          90
                  ....*....|....*....
gi 1377224709 259 RCLARNALGQAEASATLTV 277
Cdd:pfam07679  72 TCVATNSAGEAEASAELTV 90

Kazal type serine protease inhibitors and follistatin-like domains. Kazal inhibitors inhibit serine proteases, such as, trypsin, chyomotrypsin, avian ovomucoids, and elastases. The inhibitory domain has one reactive site peptide bond, which serves the cognate enzyme as substrate. The reactive site peptide bond is a combining loop which has an identical conformation in all Kazal inhibitors and in all enzyme/inhibitor complexes. These Kazal domains (small hydrophobic core of alpha/beta structure with 3 to 4 disulfide bonds) often occur in tandem arrays. Similar domains are also present in follistatin (FS) and follistatin-like family members, which play an important role in tissue specific regulation. The FS domain consists of an N-terminal beta hairpin (FOLN/EGF-like domain) and a Kazal-like domain and has five disulfide bonds. Although the Kazal-like FS substructure is similar to Kazal proteinase inhibitors, no FS domain has yet been shown to be a proteinase inhibitor. Follistatin-like family members include SPARC, also known as, BM-40 or osteonectin, the Gallus gallus Flik protein, as well as, agrin which has a long array of FS domains. The kazal-type inhibitor domain has also been detected in an extracellular loop region of solute carrier 21 (SLC21) family members (organic anion transporters) , which may regulate the specificity of anion uptake. The distant homolog, Ascidian trypsin inhibitor, is included in this CD.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|
gi 1377224709 136 RSQRPLCGSDGRTYAQICRLQEAARaRLDANLTVVHPGPC 175
Cdd:cd00104     3 KEYDPVCGSDGKTYSNECHLGCAAC-RSGRSITVAHNGPC 41

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 179 PQILSQPHNIWNVTGQDVIFGCEVFAYPMASIEWRKDGLDIQlpgDDPHISVQFRGGPQKFEvtgwlqIQALRPSDEGTY 258
Cdd:pfam07679   1 PKFTQKPKDVEVQEGESARFTCTVTGTPDPEVSWFKDGQPLR---SSDRFKVTYEGGTYTLT------ISNVQPDDSGKY 71

                          90
                  ....*....|....*....
gi 1377224709 259 RCLARNALGQAEASATLTV 277
Cdd:pfam07679  72 TCVATNSAGEAEASAELTV 90

Fifth Ig-like domain of Roundabout (Robo) homolog 1/2, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the fifth Ig-like domain of Roundabout (Robo) homolog 1/2 and similar domains. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, -2, and -3), and three mammalian Slit homologs (Slit-1,-2, -3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, -2, and -3 are expressed by commissural neurons in the vertebrate spinal cord and Slits 1, -2, -3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of slit responsiveness, antagonizes slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit2 has been shown by surface plasmon resonance experiments and mutational analysis to be is the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. The fifth Ig-like domain of Robo 1 and 2 is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 181 ILSQPHNIWNVTGQDVIFGCEVFAYPMASIEWRKDGldIQLPGDDPHISVQFRGGpqkfevtgwLQIQALRPSDEGTYRC 260
Cdd:cd20952     2 ILQGPQNQTVAVGGTVVLNCQATGEPVPTISWLKDG--VPLLGKDERITTLENGS---------LQIKGAEKSDTGEYTC 70

                          90
                  ....*....|....*..
gi 1377224709 261 LARNALGQAEASATLTV 277
Cdd:cd20952    71 VALNLSGEATWSAVLDV 87

Insulin growth factor-binding protein homologues; High affinity binding partners of insulin-like growth factors.

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1377224709   60 CAPCRPEECAA-PRGCLAGRVRDACGCCWECANLEGQLCDLDpsanfYGRCGEQLECRLDAG 120
Cdd:smart00121   3 CPPCDPARCPPcPPGCAELVRLDGCGCCPVCARQEGEPCGVY-----TPRCAPGLRCQPPPG 59

Kazal type serine protease inhibitors; Kazal type serine protease inhibitors and follistatin-like domains.

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|
gi 1377224709  136 RSQRPLCGSDGRTYAQICRLQEAARaRLDANLTVVHPGPC 175
Cdd:smart00280   8 REYDPVCGSDGVTYSNECHLCKAAC-ESGKSIEVKHDGPC 46

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 179 PQILSQPHNIWNVTGQDVIFGCEVFAYPMASIEWRKDGLDIQlpgDDPHISVQFRGGPQKFEvtgwlqIQALRPSDEGTY 258
Cdd:pfam07679   1 PKFTQKPKDVEVQEGESARFTCTVTGTPDPEVSWFKDGQPLR---SSDRFKVTYEGGTYTLT------ISNVQPDDSGKY 71

                          90
                  ....*....|....*....
gi 1377224709 259 RCLARNALGQAEASATLTV 277
Cdd:pfam07679  72 TCVATNSAGEAEASAELTV 90

Fifth Ig-like domain of Roundabout (Robo) homolog 1/2, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the fifth Ig-like domain of Roundabout (Robo) homolog 1/2 and similar domains. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, -2, and -3), and three mammalian Slit homologs (Slit-1,-2, -3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, -2, and -3 are expressed by commissural neurons in the vertebrate spinal cord and Slits 1, -2, -3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of slit responsiveness, antagonizes slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit2 has been shown by surface plasmon resonance experiments and mutational analysis to be is the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. The fifth Ig-like domain of Robo 1 and 2 is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 181 ILSQPHNIWNVTGQDVIFGCEVFAYPMASIEWRKDGldIQLPGDDPHISVQFRGGpqkfevtgwLQIQALRPSDEGTYRC 260
Cdd:cd20952     2 ILQGPQNQTVAVGGTVVLNCQATGEPVPTISWLKDG--VPLLGKDERITTLENGS---------LQIKGAEKSDTGEYTC 70

                          90
                  ....*....|....*..
gi 1377224709 261 LARNALGQAEASATLTV 277
Cdd:cd20952    71 VALNLSGEATWSAVLDV 87

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 179 PQILSQPHNIWNVTGQDVIFGCEVFAYPMASIEWRKDGldiQLPGDDPHISVQFRGGpqkfevTGWLQIQALRPSDEGTY 258
Cdd:pfam13927   2 PVITVSPSSVTVREGETVTLTCEATGSPPPTITWYKNG---EPISSGSTRSRSLSGS------NSTLTISNVTRSDAGTY 72

                  ....*.
gi 1377224709 259 RCLARN 264
Cdd:pfam13927  73 TCVASN 78

Third immunoglobulin (Ig)-like domain in Robo (roundabout) receptors; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the third immunoglobulin (Ig)-like domain in Robo (roundabout) receptors. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, Robo2, Robo3), and three mammalian Slit homologs (Slit-1,Slit-2, Slit-3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, Robo2, and Robo3 are expressed by commissural neurons in the vertebrate spinal cord and Slit-1, Slit-2, and Slit-3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of Slit responsiveness, antagonizes Slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit2 has been shown by surface plasmon resonance experiments and mutational analysis to be the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 182 LSQPHNIWNVTGQDVIFGCEVFAYPMASIEWRKDGldiqlpGDDPHISVQFRggPQKFevtgwLQIQALRPSDEGTYRCL 261
Cdd:cd05725     1 VKRPQNQVVLVDDSAEFQCEVGGDPVPTVRWRKED------GELPKGRYEIL--DDHS-----LKIRKVTAGDMGSYTCV 67

                          90
                  ....*....|....*.
gi 1377224709 262 ARNALGQAEASATLTV 277
Cdd:cd05725    68 AENMVGKIEASATLTV 83

Immunoglobulin domain; The members here are composed of the immunoglobulin (Ig) domain found in the Ig superfamily. The Ig superfamily is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. Members of this group are components of immunoglobulin, neuroglia, cell surface glycoproteins, including T-cell receptors, CD2, CD4, CD8, and membrane glycoproteins, including butyrophilin and chondroitin sulfate proteoglycan core protein. A predominant feature of most Ig domains is a disulfide bridge connecting the two beta-sheets with a tryptophan residue packed against the disulfide bond. Ig superfamily (IgSF) domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Typically, the V-set domains have A, B, E, and D strands in one sheet and A', G, F, C, C' and C" in the other. The structures in C1-set are smaller than those in the V-set; they have one beta sheet that is formed by strands A, B, E, and D and the other by strands G, F, C, and C'. Moreover, a C1-set Ig domain contains a short C' strand (three residues) and lacks A' and C" strand. Unlike other Ig domain sets, C2-set structures do not have a D strand. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1377224709 196 VIFGCEVFAYPMASIEWRKDGLDIQLPGDDPHISVQfrggpqkfeVTGWLQIQALRPSDEGTYRCLARNALGQAEASAT 274
Cdd:cd00096     1 VTLTCSASGNPPPTITWYKNGKPLPPSSRDSRRSEL---------GNGTLTISNVTLEDSGTYTCVASNSAGGSASASV 70

Immunoglobulin domain I1 of the titin I-band and similar proteins; a member of the I-set of IgSF domains; The members here are composed of the immunoglobulin domain I1 of the titin I-band and similar proteins. Titin is a key component in the assembly and functioning of vertebrate striated muscles. By providing connections at the level of individual microfilaments, it contributes to the fine balance of forces between the two halves of the sarcomere. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. The two sheets are linked together by a conserved disulfide bond between B strand and F strand. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. The Ig I1 domain of the titin I-band is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 179 PQILS--QPHNIWNvtGQDVIFGCEVFAYPMASIEWRKDGLDIQLPGDDPHISVQFRGGPQKfevtgwLQIQALRPSDEG 256
Cdd:cd20951     1 PEFIIrlQSHTVWE--KSDAKLRVEVQGKPDPEVKWYKNGVPIDPSSIPGKYKIESEYGVHV------LHIRRVTVEDSA 72

                          90       100
                  ....*....|....*....|.
gi 1377224709 257 TYRCLARNALGQAEASATLTV 277
Cdd:cd20951    73 VYSAVAKNIHGEASSSASVVV 93

First immunoglobulin (Ig)-like constant domain in Robo (roundabout) receptors, and similar domains; The members here are composed of the first immunoglobulin (Ig)-like domain in Roundabout (Robo) receptors. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, Robo2, and Robo3), and three mammalian Slit homologs (Slit1, Slit2, Slit3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, Robo2, and Robo3 are expressed by commissural neurons in the vertebrate spinal cord and Slit1, Slit2,and Slit3 are expressed at the ventral midline. Robo3 is a divergent member of the Robo family which instead of being a positive regulator of Slit responsiveness, antagonizes Slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit2 has been shown by surface plasmon resonance experiments and mutational analysis to be is the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 179 PQILSQPHNIWNVTGQDVIFGCEVFAYPMASIEWRKDGLDIQLPGDDP--HISVQFRGGPQKFEVTGWLQIQalrpSDEG 256
Cdd:cd07693     1 PRIVEHPSDLIVSKGDPATLNCKAEGRPTPTIQWLKNGQPLETDKDDPrsHRIVLPSGSLFFLRVVHGRKGR----SDEG 76

                          90       100
                  ....*....|....*....|..
gi 1377224709 257 TYRCLARNALGQA-EASATLTV 277
Cdd:cd07693    77 VYVCVAHNSLGEAvSRNASLEV 98

Fifth immunoglobulin (Ig) domain of contactin; The members here are composed of the fifth immunoglobulin (Ig) domain of contactins. Contactins are neural cell adhesion molecules and are comprised of six Ig domains followed by four fibronectin type III (FnIII) domains anchored to the membrane by glycosylphosphatidylinositol. The first four Ig domains form the intermolecular binding fragment, which arranges as a compact U-shaped module via contacts between Ig domains 1 and 4, and between Ig domains 2 and 3. Contactin-2 (TAG-1, axonin-1) may play a part in the neuronal processes of neurite outgrowth, axon guidance and fasciculation, and neuronal migration. This group also includes contactin-1 and contactin-5. The different contactins show different expression patterns in the central nervous system. During development and in adulthood, contactin-2 is transiently expressed in subsets of central and peripheral neurons. Contactin-5 is expressed specifically in the rat postnatal nervous system, peaking at about 3 weeks postnatal, and a lack of contactin-5 (NB-2) results in an impairment of neuronal activity in the rat auditory system. Contactin-5 is highly expressed in the adult human brain in the occipital lobe and in the amygdala. Contactin-1 is differentially expressed in tumor tissues and may, through a RhoA mechanism, facilitate invasion and metastasis of human lung adenocarcinoma.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 191 VTGQDVIFGCEVFAYPMASIEWRKDGldiQLPGDDPHISVQFRGGpqkfevtgwLQIQALRPSDEGTYRCLARNALGQAE 270
Cdd:cd04969    15 AKGGDVIIECKPKASPKPTISWSKGT---ELLTNSSRICILPDGS---------LKIKNVTKSDEGKYTCFAVNFFGKAN 82

                  ....*..
gi 1377224709 271 ASATLTV 277
Cdd:cd04969    83 STGSLSV 89

Third immunoglobulin (Ig)-like domain of the L1 cell adhesion molecule (CAM); The members here are composed of the third immunoglobulin (Ig)-like domain of the L1 cell adhesion molecule (CAM). L1 belongs to the L1 subfamily of cell adhesion molecules (CAMs) and is comprised of an extracellular region having six Ig-like domains, five fibronectin type III domains, a transmembrane region and an intracellular domain. L1 is primarily expressed in the nervous system and is involved in its development and function. L1 is associated with an X-linked recessive disorder, X-linked hydrocephalus, MASA syndrome, or spastic paraplegia type 1, that involves abnormalities of axonal growth. This group also contains the chicken neuron-glia cell adhesion molecule, Ng-CAM.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 193 GQDVIFGCEVFAYPMASIEWRKdgLDIQLPGDdphisvqfRGGPQKFevTGWLQIQALRPSDEGTYRCLARNALGQAEAS 272
Cdd:cd05876    10 GQSLVLECIAEGLPTPTVKWLR--PSGPLPPD--------RVKYQNH--NKTLQLLNVGESDDGEYVCLAENSLGSARHA 77

                  ....*
gi 1377224709 273 ATLTV 277
Cdd:cd05876    78 YYVTV 82

Insulin growth factor-binding protein homologues; High affinity binding partners of insulin-like growth factors.

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1377224709   60 CAPCRPEECAA-PRGCLAGRVRDACGCCWECANLEGQLCDLDpsanfYGRCGEQLECRLDAG 120
Cdd:smart00121   3 CPPCDPARCPPcPPGCAELVRLDGCGCCPVCARQEGEPCGVY-----TPRCAPGLRCQPPPG 59

Second immunoglobulin (Ig)-like domain in Robo (roundabout) receptors; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the second immunoglobulin (Ig)-like domain in Robo (roundabout) receptors. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of the Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, Robo2, and Robo3), and three mammalian Slit homologs (Slit-1,Slit-2, Slit-3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, Robo2, and Robo3 are expressed by commissural neurons in the vertebrate spinal cord and Slit-1, Slit-2, Slit-3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of Slit responsiveness, antagonizes Slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit-2 has been shown by surface plasmon resonance experiments and mutational analysis to be the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 1377224709 205 YPMASIEWRKDGLDIQLpgDDPHISVqfRGGpqkfevtGWLQIQALRPSDEGTYRCLARNALGQAE-ASATLTV 277
Cdd:cd05724    25 HPEPTVSWRKDGQPLNL--DNERVRI--VDD-------GNLLIAEARKSDEGTYKCVATNMVGEREsRAARLSV 87

Immunoglobulin (Ig)-like domain of human neurofascin (NF); member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin (Ig)-like domain of human neurofascin (NF). NF belongs to the L1 subfamily of cell adhesion molecules (CAMs) and is comprised of an extracellular region having six Ig-like domains and five fibronectin type III domains, a transmembrane region, and a cytoplasmic domain. NF has many alternatively spliced isoforms having different temporal expression patterns during development. NF participates in axon subcellular targeting and synapse formation, however little is known of the functions of the different isoforms. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lacks a C" strand.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 179 PQILSQPHNIWNVTGQDVIF-GCEVFAYPMASIEWRKDGLDIQLpGDDPHISVQFRGGPQKFEVTGwlqiqALRPSD-EG 256
Cdd:cd05875     1 PTITKQSAKDYIVDPRDNILiECEAKGNPVPTFHWTRNGKFFNV-AKDPRVSMRRRSGTLVIDFRG-----GGRPEDyEG 74

                          90
                  ....*....|....*.
gi 1377224709 257 TYRCLARNALGQAEAS 272
Cdd:cd05875    75 EYQCFARNKFGTALSN 90

Third immunoglobulin (Ig) domain of contactin; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the third immunoglobulin (Ig) domain of contactins. Contactins are neural cell adhesion molecules and are comprised of six Ig domains followed by four fibronectin type III (FnIII) domains anchored to the membrane by glycosylphosphatidylinositol. The first four Ig domains form the intermolecular binding fragment, which arranges as a compact U-shaped module via contacts between Ig domains 1 and 4, and between Ig domains 2 and 3. Contactin-2 (TAG-1, axonin-1) may play a part in the neuronal processes of neurite outgrowth, axon guidance and fasciculation, and neuronal migration. This group also includes contactin-1 and contactin-5. The different contactins show different expression patterns in the central nervous system. During development and in adulthood, contactin-2 is transiently expressed in subsets of central and peripheral neurons. Contactin-5 is expressed specifically in the rat postnatal nervous system, peaking at about 3 weeks postnatal, and a lack of contactin-5 (NB-2) results in an impairment of neuronal activity in the rat auditory system. Contactin-5 is highly expressed in the adult human brain in the occipital lobe and in the amygdala. Contactin-1 is differentially expressed in tumor tissues and may, through a RhoA mechanism, facilitate invasion and metastasis of human lung adenocarcinoma. This group belongs to the I-set of IgSF domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 184 QPHNIWNVTGQDVIFGCEVFAYPMASIEWRK-DGLDIqlpgddphisvqfrggPQKFEVT--GWLQIQALRPSDEGTYRC 260
Cdd:cd04968     7 FPADTYALKGQTVTLECFALGNPVPQIKWRKvDGSPS----------------SQWEITTsePVLEIPNVQFEDEGTYEC 70

                          90
                  ....*....|....*..
gi 1377224709 261 LARNALGQAEASATLTV 277
Cdd:cd04968    71 EAENSRGKDTVQGRIIV 87

Third immunoglobulin (Ig)-like domain of Neural Cell Adhesion Molecule 1 (NCAM-1); member of the I-set of IgSF domains; The members here are composed of the third immunoglobulin (Ig)-like domain of Neural Cell Adhesion Molecule (NCAM-1). NCAM plays important roles in the development and regeneration of the central nervous system, in synaptogenesis and neural migration. NCAM mediates cell-cell and cell-substratum recognition and adhesion via homophilic (NCAM-NCAM), and heterophilic (NCAM-non-NCAM), interactions. NCAM is expressed as three major isoforms having different intracellular extensions. The extracellular portion of NCAM has five N-terminal Ig-like domains and two fibronectin type III domains. The double zipper adhesion complex model for NCAM homophilic binding involves Ig1, Ig2, and Ig3. By this model, Ig1 and Ig2 mediate dimerization of NCAM molecules situated on the same cell surface (cis interactions), and Ig3 domains mediate interactions between NCAM molecules expressed on the surface of opposing cells (trans interactions) through binding to the Ig1 and Ig2 domains. The adhesive ability of NCAM is modulated by the addition of polysialic acid chains to the fifth Ig-like domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 192 TGQDVIFGCEVFAYPMASIEWRKDGLDIQlPGDDPHISVQfrggpQKFEVTgwlqIQALRPSDEGTYRCLARNALGQAEA 271
Cdd:cd05730    17 LGQSVTLACDADGFPEPTMTWTKDGEPIE-SGEEKYSFNE-----DGSEMT----ILDVDKLDEAEYTCIAENKAGEQEA 86

                  ....*.
gi 1377224709 272 SATLTV 277
Cdd:cd05730    87 EIHLKV 92

Immunoglobulin domain; Members of the immunoglobulin superfamily are found in hundreds of proteins of different functions. Examples include antibodies, the giant muscle kinase titin and receptor tyrosine kinases. Immunoglobulin-like domains may be involved in protein-protein and protein-ligand interactions.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 193 GQDVIFGCEV-FAYPMASIEWRKDGLDIQLPGDDPHISVQFRGGPqkfevtgwLQIQALRPSDEGTYRCLARNALGQAEA 271
Cdd:pfam00047  11 GDSATLTCSAsTGSPGPDVTWSKEGGTLIESLKVKHDNGRTTQSS--------LLISNVTKEDAGTYTCVVNNPGGSATL 82

                  ....
gi 1377224709 272 SATL 275
Cdd:pfam00047  83 STSL 86

agrin-responsive first immunoglobulin-like domains (Ig1) of the MuSK ectodomain; a member of the I-set of IgSF domains; The members here are composed of the first immunoglobulin-like domains (Ig1) of the Muscle-specific kinase (MuSK). MuSK is a receptor tyrosine kinase specifically expressed in skeletal muscle, where it plays a central role in the formation and maintenance of the neuromuscular junction (NMJ). MuSK is activated by agrin, a neuron-derived heparan sulfate proteoglycan. The activation of MUSK in myotubes regulates the formation of NMJs through the regulation of different processes including the specific expression of genes in subsynaptic nuclei, the reorganization of the actin cytoskeleton and the clustering of the acetylcholine receptors (AChR) in the postsynaptic membrane. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of the MuSK lacks this strand and thus it belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 181 ILSQPHNIWNVT---GQDVIFGCEVFAYPMASIEWRKDGLDIQLpgddphisvqfrgGPQKFEVTGW---LQIQALRPSD 254
Cdd:cd20970     2 VISTPQPSFTVTareGENATFMCRAEGSPEPEISWTRNGNLIIE-------------FNTRYIVRENgttLTIRNIRRSD 68

                          90       100
                  ....*....|....*....|....
gi 1377224709 255 EGTYRCLARN-ALGQAEASATLTV 277
Cdd:cd20970    69 MGIYLCIASNgVPGSVEKRITLQV 92

Immunoglobulin (Ig)-like domain of the L1 cell adhesion molecule (CAM) and similar proteins; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin (Ig)-like domain of the L1 cell adhesion molecule (CAM). L1 belongs to the L1 subfamily of cell adhesion molecules (CAMs) and is comprised of an extracellular region having six Ig-like domains and five fibronectin type III domains, a transmembrane region and an intracellular domain. L1 is primarily expressed in the nervous system and is involved in its development and function. L1 is associated with an X-linked recessive disorder, X-linked hydrocephalus, MASA syndrome, or spastic paraplegia type 1, that involves abnormalities of axonal growth. This group also contains NrCAM [Ng(neuronglia)CAM-related cell adhesion molecule], which is primarily expressed in the nervous system, and human neurofascin. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lacks a C" strand.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1377224709 195 DVIFGCEVFAYPMASIEWRKDGLDIQlPGDDPHISVQFRGGpqkfevTGWLQIQALRPSD-EGTYRCLARNALGQA 269
Cdd:cd05733    18 NITIKCEAKGNPQPTFRWTKDGKFFD-PAKDPRVSMRRRSG------TLVIDNHNGGPEDyQGEYQCYASNELGTA 86

Kazal type serine protease inhibitors; Kazal type serine protease inhibitors and follistatin-like domains.

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|
gi 1377224709  136 RSQRPLCGSDGRTYAQICRLQEAARaRLDANLTVVHPGPC 175
Cdd:smart00280   8 REYDPVCGSDGVTYSNECHLCKAAC-ESGKSIEVKHDGPC 46

First Ig-like domain of the giant muscle protein titin Z1z2 in the sarcomeric Z-disk and similar proteins; a member of the I-set of IgSF domains; The members here are composed of the first immunoglobulin (Ig)-like domain of the giant muscle protein titin Z1z2 in the sarcomeric Z-disk and similar proteins. Titin is a key component in the assembly and functioning of vertebrate striated muscles. By providing connections at the level of individual microfilaments, it contributes to the fine balance of forces between the two halves of the sarcomere. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of the titin Z1z2 lacks this strand and thus it belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 193 GQDVIFGCEVFAYPMASIEWRKDGLDIQLpGDDPHISVQFRGGPQKFEVTgwlqiqALRPSDEGTYRCLARNALGQAEAS 272
Cdd:cd20974    15 GSTATFEAHVSGKPVPEVSWFRDGQVIST-STLPGVQISFSDGRAKLSIP------AVTKANSGRYSLTATNGSGQATST 87

                  ....*.
gi 1377224709 273 ATLTVL 278
Cdd:cd20974    88 AELLVL 93

Third immunoglobulin (Ig)-like domain of fibroblast growth factor receptor (FGFR); member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the third immunoglobulin (Ig)-like domain of fibroblast growth factor receptor (FGFR). Fibroblast growth factors (FGFs) participate in morphogenesis, development, angiogenesis, and wound healing. These FGF-stimulated processes are mediated by four FGFR tyrosine kinases (FGRF1-4). FGFRs are comprised of an extracellular portion consisting of three Ig-like domains, a transmembrane helix, and a cytoplasmic portion having protein tyrosine kinase activity. The highly conserved Ig-like domains 2 and 3, and the linker region between D2 and D3 define a general binding site for FGFs. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 185 PHNIWNVTGQDVIFGCEVFAYPMASIEWRK----DGlDIQLPGDDPHISVQFRGGPQKFEVTGWLQIQALRPSDEGTYRC 260
Cdd:cd04974     8 PANQTVVLGSDVEFHCKVYSDAQPHIQWLKhvevNG-SKYGPDGLPYVTVLKVAGVNTTGEENTLTISNVTFDDAGEYIC 86

                          90
                  ....*....|....*.
gi 1377224709 261 LARNALGQAEASATLT 276
Cdd:cd04974    87 LAGNSIGLSFHSAWLT 102

agrin-responsive second immunoglobulin-like domains (Ig2) of the Muscle-specific kinase (MuSK) ectodomain; a member of the I-set of Ig superfamily domains; The members here are composed of the second immunoglobulin-like (Ig) domains of the Muscle-specific kinase (MuSK) ectodomain. MuSK is a receptor tyrosine kinase specifically expressed in skeletal muscle, where it plays a central role in the formation and maintenance of the neuromuscular junction (NMJ). MuSK is activated by agrin, a neuron-derived heparan sulfate proteoglycan. The activation of MUSK in myotubes regulates the formation of NMJs through the regulation of different processes including the specific expression of genes in subsynaptic nuclei, the reorganization of the actin cytoskeleton and the clustering of the acetylcholine receptors (AChR) in the postsynaptic membrane. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of the MuSK lacks this strand and thus it belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 180 QILSQPHNIWNVTGQDVIFGCEVFAYPMASIEWRKDGLDIQlpgDDPHISVqfrggpqkFEvTGWLQIQALRPSDEGTYR 259
Cdd:cd20968     1 KITRPPTNVTIIEGLKAVLPCTTMGNPKPSVSWIKGDDLIK---ENNRIAV--------LE-SGSLRIHNVQKEDAGQYR 68

                          90
                  ....*....|
gi 1377224709 260 CLARNALGQA 269
Cdd:cd20968    69 CVAKNSLGIA 78

Third immunoglobulin-like domain of the human WFIKKN (WAP, follistatin, immunoglobulin, Kunitz and NTR domain-containing protein), and similar domains; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the third immunoglobulin-like domain of the human WFIKKN (WAP, follistatin, immunoglobulin, Kunitz and NTR domain-containing protein) and similar proteins. WFIKKN is a secreted protein that consists of multiple types of protease inhibitory modules, including two tandem Kunitz-type protease inhibitor-domains. The Ig superfamily is a heterogenous group of proteins built on a common fold comprised of a sandwich of two beta sheets. Members of the Ig superfamily are components of immunoglobulin, neuroglia, cell surface glycoproteins, such as T-cell receptors, CD2, CD4, CD8, and membrane glycoproteins, such as butyrophilin and chondroitin sulfate proteoglycan core protein. A predominant feature of most Ig domains is a disulfide bridge connecting the two beta-sheets with a tryptophan residue packed against the disulfide bond. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 179 PQILSQPHNIWNVTGQDVIFGCEVFAYPMASIEWRKdgldiQLPGDDPHISV--QFRGgpqKFEVT--GWLQIQALRPSD 254
Cdd:cd05765     1 PALVNSPTHQTVKVGETASFHCDVTGRPQPEITWEK-----QVPGKENLIMRpnHVRG---NVVVTniGQLVIYNAQPQD 72

                          90       100
                  ....*....|....*....|...
gi 1377224709 255 EGTYRCLARNALGQAEASATLTV 277
Cdd:cd05765    73 AGLYTCTARNSGGLLRANFPLSV 95

Seventh immunoglobulin domain of the Drosophila melanogaster Dscam protein, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the seventh immunoglobulin domain of the Drosophila melanogaster Down syndrome cell adhesion molecule (DSCAM) protein and similar proteins. Down syndrome cell adhesion molecule (DSCAM) is a cell adhesion molecule that plays critical roles in neural development, including axon guidance and branching, axon target recognition, self-avoidance and synaptic formation. DSCAM belongs to the immunoglobulin superfamily and contributes to defects in the central nervous system in Down syndrome patients. Vertebrate DSCAMs differ from Drosophila Dscam1 in that they lack the extensive alternative splicing that occurs in the insect gene. Drosophila melanogaster Dscam has 38,016 isoforms generated by the alternative splicing of four variable exon clusters, which allows every neuron in the fly to display a distinctive set of Dscam proteins on its cell surface. Drosophila Dscam1 is a cell-surface protein that plays important roles in neural development and axon tiling of neurons. It is shown that thousands of isoforms bind themselves through specific homophilic (self-binding) interactions, a process which mediates cellular self-recognition. Drosophila Dscam2 is also alternatively spliced and plays a key role in the development of two visual system neurons, monopolar cells L1 and L2. This group is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 179 PQILSQPHNIWNVTGQDVIFGCEVFAYPMASIEWRKDgldiqlPGDDPHISVQFRGGPQ-KFEVTGWLQIQALRPSDEGT 257
Cdd:cd20954     2 PRWIVEPVDANVAAGQDVMLHCQADGFPTPTVTWKKA------TGSTPGEYKDLLYDPNvRILPNGTLVFGHVQKENEGH 75

                          90
                  ....*....|
gi 1377224709 258 YRCLARNALG 267
Cdd:cd20954    76 YLCEAKNGIG 85

Second immunoglobulin (Ig)-like domain of fibroblast growth factor (FGF) receptor, and similar domains; member of the I-set of IgSF domains; The members here are composed of the second immunoglobulin (Ig)-like domain of fibroblast growth factor (FGF) receptor. FGF receptors bind FGF signaling polypeptides. FGFs participate in multiple processes such as morphogenesis, development, and angiogenesis. FGFs bind to four FGF receptor tyrosine kinases (FGFR1, FGFR2, FGFR3, FGFR4). Receptor diversity is controlled by alternative splicing producing splice variants with different ligand binding characteristics and different expression patterns. FGFRs have an extracellular region comprised of three Ig-like domains, a single transmembrane helix, and an intracellular tyrosine kinase domain. Ligand binding and specificity reside in the Ig-like domains 2 and 3, and the linker region that connects these two. FGFR activation and signaling depend on FGF-induced dimerization, a process involving cell surface heparin or heparin sulfate proteoglycans. This group also contains fibroblast growth factor (FGF) receptor like-1(FGFRL1). FGFRL1 does not have a protein tyrosine kinase domain at its C-terminus; neither does its cytoplasmic domain appear to interact with a signaling partner. It has been suggested that FGFRL1 may not have any direct signaling function, but instead acts as a decoy receptor trapping FGFs and preventing them from binding other receptors.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1377224709 193 GQDVIFGCEVFAYPMASIEWRKDGLDIQlpgddPHisvqFRGGPQKFEVTGW-LQIQALRPSDEGTYRCLARNALGQAEA 271
Cdd:cd05729    19 ANKVRLECGAGGNPMPNITWLKDGKEFK-----KE----HRIGGTKVEEKGWsLIIERAIPRDKGKYTCIVENEYGSINH 89

                  ....*.
gi 1377224709 272 SATLTV 277
Cdd:cd05729    90 TYDVDV 95

Immunoglobulin (Ig)-like domain of the human basement membrane heparan sulfate proteoglycan perlecan and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain of the human basement membrane heparan sulfate proteoglycan perlecan, also known as HSPG2, and similar proteins. Perlecan consists of five domains: domain I has three putative heparan sulfate attachment sites, domain II has four LDL receptor-like repeats, and one Ig-like repeat, domain III resembles the short arm of laminin chains, domain IV has multiple Ig-like repeats (21 repeats in human perlecan), and domain V resembles the globular G domain of the laminin A chain and internal repeats of EGF. Perlecan may participate in a variety of biological functions including cell binding, LDL-metabolism, basement membrane assembly and selective permeability, calcium binding, and growth- and neurite-promoting activities.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 1377224709 193 GQDVIFGCEVFAYPMASIEWRkdgLDIQLPGDDPHISVQFRGGpqkfevTGWLQIQALRPSDEGTYRCLARNALG 267
Cdd:cd05743     1 GETVEFTCVATGVPTPIINWR---LNWGHVPDSARVSITSEGG------YGTLTIRDVKESDQGAYTCEAINTRG 66

Sixth immunoglobulin domain of the Drosophila melanogaster Dscam protein, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the sixth immunoglobulin domain of the Drosophila melanogaster Down syndrome cell adhesion molecule (DSCAM) protein and similar proteins. Down syndrome cell adhesion molecule (DSCAM) is a cell adhesion molecule that plays critical roles in neural development, including axon guidance and branching, axon target recognition, self-avoidance and synaptic formation. DSCAM belongs to the immunoglobulin superfamily and contributes to defects in the central nervous system in Down syndrome patients. Vertebrate DSCAMs differ from Drosophila Dscam1 in that they lack the extensive alternative splicing that occurs in the insect gene. Drosophila melanogaster Dscam has 38,016 isoforms generated by the alternative splicing of four variable exon clusters, which allows every neuron in the fly to display a distinctive set of Dscam proteins on its cell surface. Drosophila Dscam1 is a cell-surface protein that plays important roles in neural development and axon tiling of neurons. It is shown that thousands of isoforms bind themselves through specific homophilic (self-binding) interactions, a process which mediates cellular self-recognition. Drosophila Dscam2 is also alternatively spliced and plays a key role in the development of two visual system neurons, monopolar cells L1 and L2. This group is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1377224709 206 PMaSIEWRKDGLDIQlpgDDPHISVQfRGGPQkfevTGWLQIQALRPSDEGTYRCLARNALGQAEASATLTV 277
Cdd:cd20959    32 PL-NIRWTLDGQPIS---DDLGITVS-RLGRR----SSILSIDSLEASHAGNYTCHARNSAGSASYTAPLTV 94