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 1343294268  18 VSYLQISALSTTGLLVCPDLKEFISSNADGKIQWYKGAILLDKGNKEFLSAGDPTRLLISNTSMDDAGYYRCVMTFTYNG 97
Cdd:cd05897     1 ISYPQILFTSTSGKLVCPDLSEFTINRTDVEIQWYKDSLLLDKDNEKFLSVKGSTHLLIHDVSLNDSGYYTCKLTFTHEG 80

                          90
                  ....*....|....*
gi 1343294268  98 QEYNITRNIELRVKG 112
Cdd:cd05897    81 KKYNITRSIELRIVK 95

Second immunoglobulin (Ig)-like domain of interleukin-1 receptor-2 (IL1R2), and similar domains; The members here are composed of the second immunoglobulin (Ig)-like domain of interleukin-1 receptor-2 (IL1R2). IL-1 alpha and IL-1 beta are cytokines which participate in the regulation of inflammation, immune responses, and hematopoiesis. These cytokines bind to the IL-1 receptor type 1 (IL1R1), which is activated on additional association with interleukin-1 receptor accessory protein (IL1RAP). IL-1 also binds the IL-1 receptor, type II (IL1R2) represented in this group. Mature IL1R2 consists of three IG-like domains, a transmembrane domain, and a short cytoplasmic domain. It lacks the large cytoplasmic domain of mature IL1R1 and does not initiate signal transduction. A naturally occurring cytokine IL-1RA (IL-1 receptor antagonist) is widely expressed and binds to IL-1 receptors, inhibiting the binding of IL-1 alpha and IL-1 beta.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1343294268  18 VSYLQISALSTTGLLVCPDLKEFISSNADGKIQWYKGAILLDKGNKEFLSAGDPTRLLISNTSMDDAGYYRCVMTFTYNG 97
Cdd:cd05897     1 ISYPQILFTSTSGKLVCPDLSEFTINRTDVEIQWYKDSLLLDKDNEKFLSVKGSTHLLIHDVSLNDSGYYTCKLTFTHEG 80

                          90
                  ....*....|....*
gi 1343294268  98 QEYNITRNIELRVKG 112
Cdd:cd05897    81 KKYNITRSIELRIVK 95

IL-1 receptor-like protein; Provisional

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1343294268  32 LVCPDLKEFISSNADGKIQWYKGAILLdKGNKEFLSAGDPTRLLISNTSMDDAGYYRCVMTFTYNGQEYNITRNIELRV 110
Cdd:PHA02826  149 LHCYGTDGISSTFKDYTLTWYKNGNIV-LYTDRIQLRNNNSTLVIKSATHDDSGIYTCNLRFNKNSNNYNITKEYKVTI 226

Immunoglobulin like; IG domains that cannot be classified into one of IGv1, IGc1, IGc2, IG.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1343294268   32 LVCPdlkefISSNADGKIQWYKGAI--LLDKGNKEFLSAGDPTRLLISNTSMDDAGYYRCVMTFTYngqeYNITRNIELR 109
Cdd:smart00410  14 LSCE-----ASGSPPPEVTWYKQGGklLAESGRFSVSRSGSTSTLTISNVTPEDSGTYTCAATNSS----GSASSGTTLT 84

                   .
gi 1343294268  110 V 110
Cdd:smart00410  85 V 85

Second immunoglobulin (Ig)-like domain of interleukin-1 receptor-2 (IL1R2), and similar domains; The members here are composed of the second immunoglobulin (Ig)-like domain of interleukin-1 receptor-2 (IL1R2). IL-1 alpha and IL-1 beta are cytokines which participate in the regulation of inflammation, immune responses, and hematopoiesis. These cytokines bind to the IL-1 receptor type 1 (IL1R1), which is activated on additional association with interleukin-1 receptor accessory protein (IL1RAP). IL-1 also binds the IL-1 receptor, type II (IL1R2) represented in this group. Mature IL1R2 consists of three IG-like domains, a transmembrane domain, and a short cytoplasmic domain. It lacks the large cytoplasmic domain of mature IL1R1 and does not initiate signal transduction. A naturally occurring cytokine IL-1RA (IL-1 receptor antagonist) is widely expressed and binds to IL-1 receptors, inhibiting the binding of IL-1 alpha and IL-1 beta.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1343294268  18 VSYLQISALSTTGLLVCPDLKEFISSNADGKIQWYKGAILLDKGNKEFLSAGDPTRLLISNTSMDDAGYYRCVMTFTYNG 97
Cdd:cd05897     1 ISYPQILFTSTSGKLVCPDLSEFTINRTDVEIQWYKDSLLLDKDNEKFLSVKGSTHLLIHDVSLNDSGYYTCKLTFTHEG 80

                          90
                  ....*....|....*
gi 1343294268  98 QEYNITRNIELRVKG 112
Cdd:cd05897    81 KKYNITRSIELRIVK 95

IL-beta-binding protein; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1343294268   1 MSVELKVFKNTEASLPHVSYLQISALSTTGLLVCPDLKEFISSNADGKIQWYKGAILLDKGnkefLSAGDPTRLLISNTS 80
Cdd:PHA02785  110 MSLNLTIVSVSESNIDLISYPQIVNERSTGEMVCPNINAFIASNVNADIIWSGHRRLRNKR----LKQRTPGIITIEDVR 185

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1343294268  81 MDDAGYYRCVMTFTYNGQEYNITRNIELRVKGTTtepIPVIISPLETIPASLGSRLIVPCKVFLGTGTsSNTIVWWLANS 160
Cdd:PHA02785  186 KNDAGYYTCVLKYIYGDKTYNVTRIVKLEVRDRI---IPPTMQLPEGVVTSIGSNLTIACRVSLRPPT-TDADVFWISNG 261

                         170       180       190       200       210       220       230
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 1343294268 161 TFISAAYPRGRVTEGLHHQYSENDENYVEVS-LIFDPVTREDLhTDFKCVAsnprssqslhTTVKEVSSTFSWSI 234
Cdd:PHA02785  262 MYYEEDDEDGDGRISVANKIYTTDKRRVITSrLNINPVKEEDA-TTFTCMA----------FTIPSISKTVTISI 325

Second immunoglobulin (Ig)-like domain of interleukin-1 receptor (IL1R), and similar domains; The members here are composed of the second immunoglobulin (Ig)-like domain of interleukin-1 receptor (IL1R). IL-1 alpha and IL-1 beta are cytokines which participate in the regulation of inflammation, immune responses, and hematopoiesis. These cytokines bind to the IL-1 receptor type 1 (IL1R1), which is activated on additional association with interleukin-1 receptor accessory protein (IL1RAP). IL-1 also binds a second receptor designated type II (IL1R2). Mature IL1R1 consists of three IG-like domains, a transmembrane domain, and a large cytoplasmic domain. Mature IL1R2 is organized similarly except that it has a short cytoplasmic domain. The latter does not initiate signal transduction. A naturally occurring cytokine IL-1RA (IL-1 receptor antagonist) is widely expressed and binds to IL-1 receptors, inhibiting the binding of IL-1 alpha and IL-1 beta. This group also contains ILIR-like 1 (IL1R1L) which maps to the same chromosomal location as IL1R1 and IL1R2.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1343294268  16 PHVSYLQISALSTTgllvCPDLKEFISSNADGKIQWYKGAILLDKGNkEFLSAGDPTRLLISNTSMDdaGYYRCVMTFTY 95
Cdd:cd20993     4 PVIAYIEYGGRTIT----CPDLDGIKPPSVSPTVTWYHECNAFGNFN-DRVPKGDKLVIHVMLEHYQ--GNYTCVVTYET 76

                          90
                  ....*....|....*..
gi 1343294268  96 NGQEYNITRNIELRVKG 112
Cdd:cd20993    77 KGRTIKLTRTVNVKVVG 93

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1343294268 119 PVIISPLETIPASLGSRLIVPCKVflgTGTSSNTIVWwlanstfisaaYPRGRVTEGLHHQYSENDENYveVSLIFDPVT 198
Cdd:pfam13927   2 PVITVSPSSVTVREGETVTLTCEA---TGSPPPTITW-----------YKNGEPISSGSTRSRSLSGSN--STLTISNVT 65

                          90
                  ....*....|....
gi 1343294268 199 REDlHTDFKCVASN 212
Cdd:pfam13927  66 RSD-AGTYTCVASN 78

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1343294268 119 PVIISPLETIPASLGSRLIVPCKVflgTGTSSNTIVWWLANSTfisaayprgrVTEGLHHQYSENDENYvevSLIFDPVT 198
Cdd:pfam07679   1 PKFTQKPKDVEVQEGESARFTCTV---TGTPDPEVSWFKDGQP----------LRSSDRFKVTYEGGTY---TLTISNVQ 64

                          90       100
                  ....*....|....*....|....*.
gi 1343294268 199 REDLHTdFKCVASNPRSSQSLHTTVK 224
Cdd:pfam07679  65 PDDSGK-YTCVATNSAGEAEASAELT 89

Third immunoglobulin domain of interleukin-1 receptor accessory protein (IL1RAP); The members here are composed of the third immunoglobulin Ig interleukin-1 receptor accessory protein (IL1RAP). The interleukin 1 receptor accessory protein (IL-1RAP), also known as IL-1R3, is a coreceptor of type 1 interleukin 1 receptor (IL-1R1) and is required for transmission of IL-1 signaling. The activated IL-1 receptor complex, which consists of IL-1R1 and IL-1RAP, induces multiple cellular responses including NF-kappa-B activation, IL-2 secretion, and IL-2 promoter activation. Signaling involves the recruitment of adapter molecules such as TOLLIP, MYD88, and IRAK1 or IRAK2 via the respective Toll/IL-1 receptor (TIR) domains of the receptor/coreceptor subunits. Moreover, IL1RAP is known to be the accessory co-receptor that activates signal transduction upon IL-36 binding to IL-36R. IL-36 cytokines, which are a subfamily of the IL-1 superfamily, bind to the IL-36 receptor (IL-36R) and use IL1RAP as a co-receptor.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1343294268 119 PVIISPLETI--PASLGSRLIVPCKVFLGTGTSSNTIVWWLANSTFISAAYPRGRVTEGLHHQYSEnDENYVEVsLIFDP 196
Cdd:cd20931     1 PQIYSPNDRVvyEKEPGEELLIPCTVYFSFLMDSRNEVWWTIDGKKPDDVTIDVTINESISYSSTE-DETRTQI-LSIKK 78

                          90       100
                  ....*....|....*....|....*....
gi 1343294268 197 VTREDLHTDFKCVASNPRSSQSLHTTVKE 225
Cdd:cd20931    79 VTPEDLKRNYVCHARNAKGEVEKAAKVKQ 107

Domain C2 of human cardiac Myosin Binding Protein C and similar domains; a member of the I-set of IgSF domains; The members here are composed of the immunoglobulin (Ig) Domain C2 of human cardiac Myosin Binding Protein C (MyBP-C) and similar domains. MyBP-C is a thick filament protein involved in the regulation of muscle contraction. Mutations in cardiac MyBP-C gene are the second most frequent cause of hypertrophic cardiomyopathy. MyBP-C binds to myosin with two binding sites, one at its C-terminus and another at its N-terminus. The N-terminal binding site, consisting of immunoglobulin (lg) domains C1 and C2 connected by a flexible linker, interacts with the S2 segment of myosin in a phosphorylation-regulated manner. The C1 and C2 Ig domains can bind to and activate or inhibit the thin filament. 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 structures of the Ig domains of MyBP-C lack this strand and thus belong to the I-set of Ig superfamily domains. 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
                  ....*....|....*....|....*....|....*....|....*....
gi 1343294268  43 SNADGKIQWYK-GAILLDKGNKEFLSAGDPTRLLISNTSMDDAGYYRCV 90
Cdd:cd20967    22 ADPDAEVKWYKdGQELQSSSKVIFESIGAKRTLTVQQASLADAGEYQCV 70