Link_domain_HAPLN_module_2; this link domain is found in the second link module of proteins similar to the vertebrate HAPLN (hyaluronan/HA and proteoglycan binding link) protein family which includes cartilage link protein. The link domain is a HA-binding domain. HAPLNs contain two contiguous link modules. Both link modules of cartilage link protein are involved in interaction with HA. In cartilage, a chondroitin sulfate proteoglycan core protein (CSPG) aggrecan forms cartilage link protein stabilized aggregates with HA. These aggregates contribute to the tissue's load bearing properties. Aggregates with other CSPGs substituting for aggregan may contribute to the structural integrity of many different tissues. Members of the vertebrate HAPLN gene family are physically linked adjacent to CSPG genes.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 228 RVYYLEHPEKLTLTEAREACQEDDATIAKVGQLFAAWKFHGLDRCDAGWLADGSVRYPVVHPHPNCGPPEPGVRSFGFPD 307
Cdd:cd03519     1 GVFYLLHPGKLTFSEAVAACQRDGAQIAKVGQLFAAWKFHGLDRCDAGWLADGSVRYPISRPRPRCGPLEPGVRSFGFPD 80

                          90
                  ....*....|.
gi 1034589777 308 PQSRLYGVYCY 318
Cdd:cd03519    81 KKHKLYGVYCY 91

Link_domain_HAPLN_module_2; this link domain is found in the second link module of proteins similar to the vertebrate HAPLN (hyaluronan/HA and proteoglycan binding link) protein family which includes cartilage link protein. The link domain is a HA-binding domain. HAPLNs contain two contiguous link modules. Both link modules of cartilage link protein are involved in interaction with HA. In cartilage, a chondroitin sulfate proteoglycan core protein (CSPG) aggrecan forms cartilage link protein stabilized aggregates with HA. These aggregates contribute to the tissue's load bearing properties. Aggregates with other CSPGs substituting for aggregan may contribute to the structural integrity of many different tissues. Members of the vertebrate HAPLN gene family are physically linked adjacent to CSPG genes.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 228 RVYYLEHPEKLTLTEAREACQEDDATIAKVGQLFAAWKFHGLDRCDAGWLADGSVRYPVVHPHPNCGPPEPGVRSFGFPD 307
Cdd:cd03519     1 GVFYLLHPGKLTFSEAVAACQRDGAQIAKVGQLFAAWKFHGLDRCDAGWLADGSVRYPISRPRPRCGPLEPGVRSFGFPD 80

                          90
                  ....*....|.
gi 1034589777 308 PQSRLYGVYCY 318
Cdd:cd03519    81 KKHKLYGVYCY 91

Link (Hyaluronan-binding);

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777  226 RGRVYYLEH--PEKLTLTEAREACQEDDATIAKVGQLFAAWKFhGLDRCDAGWLADGSVRYPVVHPHPNCGPPEPGVRSF 303
Cdd:smart00445   1 DGGVFHVEKngRYKLTFAEAREACRAQGATLATVGQLYAAWQD-GFDTCDAGWLADGSVRYPIITPRPRCGGNLPGVRQY 79

                           90
                   ....*....|....*.
gi 1034589777  304 GFPDPQSRlYGVYCYR 319
Cdd:smart00445  80 GFPDPTSR-YDAYCFN 94

Immunoglobulin V-Type;

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777  127 SVILPCRYRYepalVSPRRVRVKWWKLSENGAPEkdVLVAIGLRHRSFGD--YQGRVHLRQDK-EHDVSLEIQDLRLEDY 203
Cdd:smart00406   1 SVTLSCKFSG----STFSSYYVSWVRQPPGKGLE--WLGYIGSNGSSYYQesYKGRFTISKDTsKNDVSLTISNLRVEDT 74

                   ....*..
gi 1034589777  204 GRYRCEV 210
Cdd:smart00406  75 GTYYCAV 81

Link_domain_HAPLN_module_2; this link domain is found in the second link module of proteins similar to the vertebrate HAPLN (hyaluronan/HA and proteoglycan binding link) protein family which includes cartilage link protein. The link domain is a HA-binding domain. HAPLNs contain two contiguous link modules. Both link modules of cartilage link protein are involved in interaction with HA. In cartilage, a chondroitin sulfate proteoglycan core protein (CSPG) aggrecan forms cartilage link protein stabilized aggregates with HA. These aggregates contribute to the tissue's load bearing properties. Aggregates with other CSPGs substituting for aggregan may contribute to the structural integrity of many different tissues. Members of the vertebrate HAPLN gene family are physically linked adjacent to CSPG genes.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 228 RVYYLEHPEKLTLTEAREACQEDDATIAKVGQLFAAWKFHGLDRCDAGWLADGSVRYPVVHPHPNCGPPEPGVRSFGFPD 307
Cdd:cd03519     1 GVFYLLHPGKLTFSEAVAACQRDGAQIAKVGQLFAAWKFHGLDRCDAGWLADGSVRYPISRPRPRCGPLEPGVRSFGFPD 80

                          90
                  ....*....|.
gi 1034589777 308 PQSRLYGVYCY 318
Cdd:cd03519    81 KKHKLYGVYCY 91

Link (Hyaluronan-binding);

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777  226 RGRVYYLEH--PEKLTLTEAREACQEDDATIAKVGQLFAAWKFhGLDRCDAGWLADGSVRYPVVHPHPNCGPPEPGVRSF 303
Cdd:smart00445   1 DGGVFHVEKngRYKLTFAEAREACRAQGATLATVGQLYAAWQD-GFDTCDAGWLADGSVRYPIITPRPRCGGNLPGVRQY 79

                           90
                   ....*....|....*.
gi 1034589777  304 GFPDPQSRlYGVYCYR 319
Cdd:smart00445  80 GFPDPTSR-YDAYCFN 94

The link domain is a hyaluronan (HA)-binding domain. It functions to mediate adhesive interactions during inflammatory leukocyte homing and tumor metastasis. It is found in the CD44 receptor and in human TSG-6. TSG-6 is the protein product of the tumor necrosis factor-stimulated gene-6. TSG-6 has a strong anti-inflammatory effect in models of acute inflammation and autoimmune arthritis and plays an essential role in female fertility. This group also contains the link domains of the chondroitin sulfate proteoglycan core proteins (CSPG) including aggrecan, versican, neurocan, and brevican and the link domains of the vertebrate HAPLN (HA and proteoglycan binding link) protein family. In cartilage, aggrecan forms cartilage link protein stabilized aggregates with HA. These aggregates contribute to the tissue's load bearing properties. Aggregates in which other CSPGs substitute for aggregan might contribute to the structural integrity of many different tissues. Members of the vertebrate HPLN gene family are physically linked adjacent to CSPG genes. TSG-6 contains a single link module which supports high affinity binding with HA. The functional HA-binding domain of CD44 is an extended domain comprised of a link module flanked with N-and C- extensions. These extensions are essential for folding and functional activity. CSPGs are characterized by an N-terminal globular domain (G1 domain) containing two contiguous link modules (modules 1 and 2). Both link modules of the G1 domain of the CSPG aggrecan are involved in interaction with HA. Aggrecan in addition contains a second globular domain (G2) which contains link modules 3 and 4 which lack HA-binding activity. HAPLNs contain two contiguous link modules.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 228 RVYYLEH---PEKLTLTEAREACQEDDATIAKVGQLFAAWKFhGLDRCDAGWLADGSVRYPVVHPHPNCGPPEPGVRSFG 304
Cdd:cd01102     1 VVFHLESqngRYKLTFAEAALACKARGAHLATPGQLEAAWQD-GFDVCTAGWLADGSVRYPIVTSRPNCGGRNPGVRSYG 79

                          90
                  ....*....|....
gi 1034589777 305 FPDPQSRlYGVYCY 318
Cdd:cd01102    80 NPAPSGR-YDAYCF 92

Link_domain_CSPGs_modules_1_3; this extracellular link domain is found in the first and third link modules of the chondroitin sulfate proteoglycan core protein (CSPG) aggrecan. In addition, it is found in the first link module of three other CSPGs: versican, neurocan, and brevican. The link domain is a hyaluronan (HA)-binding domain. CSPGs are characterized by an N-terminal globular domain (G1 domain) containing two contiguous link modules (modules 1 and 2). Both link modules of the G1 domain of aggrecan are involved in interaction with HA. In addition, aggrecan contains a second globular domain (G2) which contains link modules 3 and 4. G2 appears to lack HA-binding activity. In cartilage, aggrecan forms cartilage link protein stabilized aggregates with HA. These aggregates contribute to the tissue's load bearing properties. Aggregates having other CSPGs substituting for aggrecan may contribute to the structural integrity of many different tissues. Members of the vertebrate HPLN (hyaluronan/HA and proteoglycan binding link) protein family are physically linked adjacent to CSPG genes.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 238 LTLTEAREACQEDDATIAKVGQLFAAWkFHGLDRCDAGWLADGSVRYPVVHPHPNCGPPE---PGVRSFGFPDPQSrLYG 314
Cdd:cd03517    14 LTFPRAQRACLDISAQIATPEQLLAAY-EDGFEQCDAGWLADQTVRYPIQTPREGCYGDMdgfPGVRNYGVRDPDE-LYD 91

                  ....
gi 1034589777 315 VYCY 318
Cdd:cd03517    92 VYCY 95

Immunoglobulin (Ig)-like domain of the aggrecan-like chondroitin sulfate proteoglycan core protein (CSPG); The members here are composed of the immunoglobulin (Ig)-like domain of the aggrecan-like chondroitin sulfate proteoglycan core proteins (CSPGs). Included in this group are the Ig domains of other CSPGs: versican, and neurocan. In CSPGs, this Ig-like domain is followed by hyaluronan (HA)-binding tandem repeats, and a C-terminal region with epidermal growth factor-like, lectin-like, and complement regulatory protein-like domains. Separating these N- and C-terminal regions is a nonhomologous glycosaminoglycan attachment region. In cartilage, aggrecan forms cartilage link protein stabilized aggregates with hyaluronan (HA). These aggregates contribute to the tissue's load bearing properties. Aggrecan and versican have a wide distribution in connective tissue and extracellular matrices. Neurocan is localized almost exclusively in nervous tissue. Aggregates having other CSPGs substituting for aggrecan may contribute to the structural integrity of many different tissues. Members of the vertebrate HPLN (hyaluronan/HA and proteoglycan binding link) protein family are physically linked adjacent to CSPG genes.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 125 GASVILPCRYRYEPALVSPRRV----RVKWWKLSENGAPEKD--VLVAIGLRHRSFGDYQGRVHLRQDKEH--DVSLEIQ 196
Cdd:cd05878    12 GTSVTLPCYFIDPPHPVTPSTAplapRIKWSKVSVDGKKEKEvvLLVATEGRVRVNSAYQGRVSLPNYPAIpsDATLEVQ 91

                          90       100       110
                  ....*....|....*....|....*....|....
gi 1034589777 197 DLRLEDYGRYRCEVIDGLEDESGLVELELRGRVY 230
Cdd:cd05878    92 SLRASDSGLYRCEVMHGIEDSQDTVELVVKGVVF 125

Immunoglobulin (Ig)-like domain of the chondroitin sulfate proteoglycan core protein (CSPG), neurocan; The members here are composed of the immunoglobulin (Ig)-like domain of the chondroitin sulfate proteoglycan core protein (CSPG), neurocan. In CSPGs, the Ig-like domain is followed by hyaluronan (HA)-binding tandem repeats, and a C-terminal region with epidermal growth factor-like, lectin-like, and complement regulatory protein-like domains. Separating these N- and C-terminal regions is a nonhomologous glycosaminoglycan attachment region. In cartilage, the CSPG aggrecan (not included in this group) forms cartilage link protein stabilized aggregates with HA. These aggregates contribute to the tissue's load bearing properties. Unlike aggrecan which is widely distributed in connective tissue and extracellular matrices, neurocan is localized almost exclusively in nervous tissue. Aggregates having other CSPGs substituting for aggrecan may contribute to the structural integrity of many different tissues. Members of the vertebrate HPLN (hyaluronan/HA and proteoglycan binding link) protein family are physically linked adjacent to CSPG genes.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 127 SVILPCRYRYEPALVSPRRV-RVKWWKLSEN-GAPEKDVLVAIGLRHRSFGDYQGRVHL--RQDKEHDVSLEIQDLRLED 202
Cdd:cd05902    14 SVLLPCVFTLPPSASSPPEGpRIKWTKLSTSgGQQQRPVLVARDNVVRVAKAFQGRVSLpgYPKNRYNASLVLSRLRYSD 93

                          90       100
                  ....*....|....*....|....*...
gi 1034589777 203 YGRYRCEVIDGLEDESGLVELELRGRVY 230
Cdd:cd05902    94 SGTYRCEVVLGINDEQDTVPLEVTGVVF 121

Immunoglobulin (Ig)-like domain of the chondroitin sulfate proteoglycan core protein (CSPG), aggrecan; The members here are composed of the immunoglobulin (Ig)-like domain of the chondroitin sulfate proteoglycan core protein (CSPG), aggrecan. In CSPGs, the Ig-like domain is followed by hyaluronan (HA)-binding tandem repeats, and a C-terminal region with epidermal growth factor-like, lectin-like, and complement regulatory protein-like domains. Separating these N- and C-terminal regions is a nonhomologous glycosaminoglycan attachment region. In cartilage, aggrecan forms cartilage link protein stabilized aggregates with HA. These aggregates contribute to the tissue's load bearing properties. Aggrecan has a wide distribution in connective tissue and extracellular matrices. Members of the vertebrate HPLN (hyaluronan/HA and proteoglycan binding link) protein family are physically linked adjacent to CSPG genes.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 116 PEET-LFTYQGASVILPCrYRYEP----------ALVSPRrvrVKWWKLSENgaPEKDVLVAIGLRHRSFGDYQGRVHLR 184
Cdd:cd05900     2 PLESpLRVVLGSSLLIPC-YFQDPiakdpgaptvAPLSPR---IKWSFISKE--KESVLLVATEGKVRVNTEYLDRVSLP 75

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*...
gi 1034589777 185 QDK--EHDVSLEIQDLRLEDYGRYRCEVIDGLEDESGLVELELRGRVY 230
Cdd:cd05900    76 NYPaiPSDATLEITELRSNDSGTYRCEVMHGIEDNYDTVEVQVKGIVF 123

Immunoglobulin variable (IgV)-like domain in complement receptor of the immunoglobulin superfamily (CRIg); The members here are composed of the immunoglobulin variable (IgV) region of the complement receptor of the immunoglobulin superfamily (CRIg). The N-terminal domain of CRIg (also known as Z39Ig and V-set and Ig domain-containing 4 (VSIG4) belongs to the IgV family of immunoglobulin-like domains while the C-terminal domain of CRIg belongs to the IgC family of immunoglobulin-like domains. Like all members of this family, the CRIg domain contains two beta-sheets: one composed of strands A', G, F, C, C' and C", and the other of strands B, E and D. The complement system is an important part of the innate immune system and is required for removal of pathogens from the bloodstream. After exposure to pathogens, the third component of the complement system, C3, is cleaved to C3b which, after recruitment of factor B, initiates formation of the alternative pathway convertases. CRIg, a complement receptor expressed on macrophages, binds to C3b and iC3b mediating phagocytosis of the particles. It is also a potent inhibitor of the alternative pathway convertases and a negative regulator of T cell activation. 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, 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.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 112 VVETPEETLFTYQGaSVILPCRYRYEPALVsprRVRVKWWKLSENGApekdvlVAIGLRHRSfGD------YQGRVHLRQ 185
Cdd:cd16089     2 ILEGPESITGPWKG-SVNLPCTYVPEEGYT---QVLVKWLVQRDSDP------VTIFLRDSS-GDhiqqakYRGRLEVSK 70

                          90       100
                  ....*....|....*....|....*
gi 1034589777 186 DKEHDVSLEIQDLRLEDYGRYRCEV 210
Cdd:cd16089    71 DTPGDVSLQLDTLEMDDRGHYTCQV 95

Immunoglobulin V-Type;

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777  127 SVILPCRYRYepalVSPRRVRVKWWKLSENGAPEkdVLVAIGLRHRSFGD--YQGRVHLRQDK-EHDVSLEIQDLRLEDY 203
Cdd:smart00406   1 SVTLSCKFSG----STFSSYYVSWVRQPPGKGLE--WLGYIGSNGSSYYQesYKGRFTISKDTsKNDVSLTISNLRVEDT 74

                   ....*..
gi 1034589777  204 GRYRCEV 210
Cdd:smart00406  75 GTYYCAV 81

Immunoglobulin Variable (V) domain of the Coxsackievirus and Adenovirus Receptor (CAR), and similar proteins; The members here are composed of the Variable (V) domain of the Coxsackievirus and Adenovirus Receptor (CAR), and similar proteins. CAR, which is encoded by human CXADR gene, is a cell adhesion molecule of the Immunoglobulin (Ig) superfamily. The CAR acts as a type I membrane receptor for group B1-B6 coxsackie viruses and subgroup C adenoviruses. For instance, adenovirus interacts with the coxsackievirus and adenovirus receptor to enter epithelial airway cells. The CAR is also shown to be involved in physiological processes such as neuronal and heart development, epithelial tight junction integrity, and tumor suppression. The CAR is a component of the epithelial apical junction complex that may function as a homophilic cell adhesion molecule and is essential for tight junction integrity. The CAR is also involved in transepithelial migration of leukocytes through adhesive interactions with JAML a transmembrane protein of the plasma membrane of leukocytes. The interaction between both receptors also mediates the activation of gamma-delta T-cells, a subpopulation of T-cells residing in epithelia and involved in tissue homeostasis and repair. The CAR is composed of one V-set and one C2-set Ig module, a single transmembrane helix, and an intracellular domain. This group belongs to the V-set of IgSF domains, having A, B, E and D strands in one beta-sheet and A', G, F, C, C' and C" in the other

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 111 LVVETPEETLFTYQGASVILPCRYRYEPALVSPRRVRvkwWKLSENGAPEKDVLVAIGlrHRSFGDY----QGRVHL-RQ 185
Cdd:cd20960     1 LLITSAQTEIKKVAGENVTLPCHHQLGLEDQGTLDIE---WLLLPSDKVEKVVITYSG--DRVYNHYypalKGRVAFtSN 75

                          90       100
                  ....*....|....*....|....*
gi 1034589777 186 DKEHDVSLEIQDLRLEDYGRYRCEV 210
Cdd:cd20960    76 DLSGDASLNISNLKLSDTGTYQCKV 100

Immunoglobulin Variable region-containing chitin-binding proteins; an immunoglobulin V-set domain; The members here are composed of the immunoglobulin variable (IgV) region-containing chitin-binding proteins (VCBPs). VCBPs are secreted, immune-type molecules that have been identified in both amphioxus and sea squirt (Ciona intestinalis). VCBPs, which consist of a leader peptide, two tandem N-terminal immunoglobulin V-type domains and a single C-terminal chitin-binding domain, belong to a multigene family encoding secreted proteins. The VCBPs were identified first in the cephalochordate Branchiostoma floridae and show structural similarities with V-type domains of immunoglobulins and T cell receptors, suggesting that VCBPs represent a unique gut-associated form of innate immune proteins. 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, 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. 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. This group belongs to the V-set of IgSF domains, having A, B, E and D strands in one beta-sheet and A', G, F, C, C' and C" in the other.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 125 GASVILPCRYRYEPALVSPRrvrVKWWKLSengAPEKDVLVAIGLRH---------RSFGDYQGRVHLrQDKEHDvSLEI 195
Cdd:cd20963    17 GNRVELPCSYTISPAAQPPT---ITWLKGI---SVDRAEVVFKGFKYwnetsssgeVYFGDYAGRASV-ASLTQP-TLVL 88

                          90
                  ....*....|....*
gi 1034589777 196 QDLRLEDYGRYRCEV 210
Cdd:cd20963    89 TDLKFDDWGRYWCRV 103

First immunoglobulin (Ig) variable (V) domain of rat MRC OX-2 antigen, and similar domains; The members here are composed of the first immunoglobulin (Ig) domain of rat MRC OX-2 antigen (also known as CD200) and similar proteins. MRC OX-2 is a membrane glycoprotein expressed in a variety of lymphoid and non-lymphoid cells in rats. It has a similar broad distribution pattern in humans. MRC OX-2 may regulate myeloid cell activity. The protein has an extracellular portion containing two Ig-like domains, a transmembrane portion, and a cytoplasmic portion.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 111 LVVETPEETLFtyqGASVILPCRYRyepalvSPRRVR-VKWWKLSEnGAPEkdvlvAIGLRHRSFGD-----YQGRVHLR 184
Cdd:cd05846     2 VVHTGDTRAVL---GGNATLSCNLT------LPEEVLqVTWQKIKA-SSPE-----NIVTYSKKYGVkiqpsYVRRISFT 66

                          90       100
                  ....*....|....*....|....*
gi 1034589777 185 QDKEHDVSLEIQDLRLEDYGRYRCE 209
Cdd:cd05846    67 SSGLNSTSITIWNVTLEDEGCYKCL 91

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        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 128 VILPCRYRYEPAlvsprrVRVKWWKlseNGAPEKdvlvaiglrhrsfgdyQGRVHLRQDKEHDVSLEIQDLRLEDYGRYR 207
Cdd:cd00096     1 VTLTCSASGNPP------PTITWYK---NGKPLP----------------PSSRDSRRSELGNGTLTISNVTLEDSGTYT 55

                  ...
gi 1034589777 208 CEV 210
Cdd:cd00096    56 CVA 58

Immunoglobulin variable domain (IgV); The members here are composed of the immunoglobulin variable domain (IgV). The IgV family contains the standard Ig superfamily V-set AGFCC'C"/DEB domain topology, and are components of immunoglobulin (Ig) and T cell receptors. The basic structure of Ig molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. In Ig, each chain is composed of one variable domain (IgV) and one or more constant domains (IgC); these names reflect the fact that the variability in sequences is higher in the variable domain than in the constant domain. Within the variable domain, there are regions of even more variability called the hypervariable or complementarity-determining regions (CDRs) which are responsible for antigen binding. A predominant feature of most Ig domains is the disulfide bridge connecting 2 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" strands in the other.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 124 QGASVILPCRYRyepalVSPRRVRVKWWKLSENGAPEkdVLVAIGLRHRSF-GDYQGRVHLRQDKEHDVSLEIQDLRLED 202
Cdd:cd00099    12 EGESVTLSCEVS-----SSFSSTYIYWYRQKPGQGPE--FLIYLSSSKGKTkGGVPGRFSGSRDGTSSFSLTISNLQPED 84

                          90
                  ....*....|.
gi 1034589777 203 YGRYRCEVIDG 213
Cdd:cd00099    85 SGTYYCAVSES 95

Immunoglobulin (Ig)-like domain of myelin oligodendrocyte glycoprotein (MOG); The members here are composed of the immunoglobulin (Ig)-like domain of myelin oligodendrocyte glycoprotein (MOG). MOG, a minor component of the myelin sheath, is an important CNS-specific autoantigen, linked to the pathogenesis of multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). It is a transmembrane protein having an extracellular Ig domain. MOG is expressed in the CNS on the outermost lamellae of the myelin sheath, and on the surface of oligodendrocytes, and may participate in the completion, compaction, and/or maintenance of myelin. This group also includes butyrophilin (BTN). BTN is the most abundant protein in bovine milk-fat globule membrane (MFGM).

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|
gi 1034589777 176 DYQGRVHLRQD--KEHDVSLEIQDLRLEDYGRYRCEVIDGLEDESGLVEL 223
Cdd:cd05713    62 EYRGRTELLKDaiAEGSVALRIHNVRPSDEGQYTCFFRSGSFYEEATLEL 111

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034589777 110 KLVVETPEETLFTYQGASVILPCRYRYEPalvsprRVRVKWWKlseNGAPEKDVLVaiglRHRSFGDYQGrvhlrqdkeh 189
Cdd:pfam13927   1 KPVITVSPSSVTVREGETVTLTCEATGSP------PPTITWYK---NGEPISSGST----RSRSLSGSNS---------- 57

                          90       100
                  ....*....|....*....|.
gi 1034589777 190 dvSLEIQDLRLEDYGRYRCEV 210
Cdd:pfam13927  58 --TLTISNVTRSDAGTYTCVA 76