Second immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs), and similar domains; The members here are composed of the second immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs). Interactions between IgG and FcgammaR are important to the initiation of cellular and humoral response. IgG binding to FcgammaR leads to a cascade of signals and ultimately to functions such as antibody-dependent-cellular-cytotoxicity (ADCC), endocytosis, phagocytosis, release of inflammatory mediators, etc. FcgammaR has two Ig-like domains. This group also contains FcepsilonRI which binds IgE with high affinity.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 530364648  29 WLYLQAWPNPVFEGDALTLRCQGWKNTPLSQVKFYRDGKFLHFSKENQTLSMGAATVQSRGQYSCSGQVMYipqtFTQTS 108
Cdd:cd05753    1 WLLLQAPSAVVFEGEPLTLRCHGWKDKKVHKVTYYKDGKALKFSYENSNFSIPQATLSDSGSYHCSGTVRI----KRRSS 76

                 ....*..
gi 530364648 109 ETAMVQV 115
Cdd:cd05753   77 ESVNITV 83

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 530364648   133 REGSLVTLRCQTKLHP------LRSALRLLFsfHKDGHTLQDRGPHPELCIPGAKEGDSGLYWCEVAPEGGQVQKQSpQL 206
Cdd:smart00410   7 KEGESVTLSCEASGSPppevtwYKQGGKLLA--ESGRFSVSRSGSTSTLTISNVTPEDSGTYTCAATNSSGSASSGT-TL 83

                   ..
gi 530364648   207 EV 208
Cdd:smart00410  84 TV 85

Second immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs), and similar domains; The members here are composed of the second immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs). Interactions between IgG and FcgammaR are important to the initiation of cellular and humoral response. IgG binding to FcgammaR leads to a cascade of signals and ultimately to functions such as antibody-dependent-cellular-cytotoxicity (ADCC), endocytosis, phagocytosis, release of inflammatory mediators, etc. FcgammaR has two Ig-like domains. This group also contains FcepsilonRI which binds IgE with high affinity.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 530364648  29 WLYLQAWPNPVFEGDALTLRCQGWKNTPLSQVKFYRDGKFLHFSKENQTLSMGAATVQSRGQYSCSGQVMYipqtFTQTS 108
Cdd:cd05753    1 WLLLQAPSAVVFEGEPLTLRCHGWKDKKVHKVTYYKDGKALKFSYENSNFSIPQATLSDSGSYHCSGTVRI----KRRSS 76

                 ....*..
gi 530364648 109 ETAMVQV 115
Cdd:cd05753   77 ESVNITV 83

Immunoglobulin domain; This domain contains immunoglobulin-like domains.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 530364648   29 WLYLQAWPNPVFEGDALTLRCQGWKNtPLSQVKFYRDGKFLhfsKENQTLSMGAATVQSRGQYSCSGQ 96
Cdd:pfam13895   1 KPVLTPSPTVVTEGEPVTLTCSAPGN-PPPSYTWYKDGSAI---SSSPNFFTLSVSAEDSGTYTCVAR 64

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 530364648   133 REGSLVTLRCQTKLHP------LRSALRLLFsfHKDGHTLQDRGPHPELCIPGAKEGDSGLYWCEVAPEGGQVQKQSpQL 206
Cdd:smart00410   7 KEGESVTLSCEASGSPppevtwYKQGGKLLA--ESGRFSVSRSGSTSTLTISNVTPEDSGTYTCAATNSSGSASSGT-TL 83

                   ..
gi 530364648   207 EV 208
Cdd:smart00410  84 TV 85

Immunoglobulin (Ig)-like domain found in Leukocyte Ig-like receptors, Natural killer inhibitory receptors (KIRs) and similar domains; member of Immunoglobulin Constant-2 set of IgSF domains; The members here are composed of the first and second immunoglobulin (Ig)-like domains found in Leukocyte Ig-like receptors (LILRs), Natural killer inhibitory receptors (KIRs, also known as also known as cluster of differentiation (CD) 158), and similar proteins. This group includes LILRB1 (also known as LIR-1), LILRA5 (also known as LIR9), an activating natural cytotoxicity receptor NKp46, the immune-type receptor glycoprotein VI (GPVI), and the IgA-specific receptor Fc-alphaRI (also known as cluster of differentiation (CD) 89). LILRs are a family of immunoreceptors expressed on expressed on T and B cells, on monocytes, dendritic cells, and subgroups of natural killer (NK) cells. The human LILR family contains nine proteins (LILRA1-3, and 5, and LILRB1-5). From functional assays, and as the cytoplasmic domains of various LILRs, for example LILRB1, LILRB2 (also known as LIR-2), and LILRB3 (also known as LIR-3) contain immunoreceptor tyrosine-based inhibitory motifs (ITIMs), it is thought that LIR proteins are inhibitory receptors. Of the eight LIR family proteins, only LILRB1, and LILRB2, show detectable binding to class I MHC molecules; ligands for the other members have yet to be determined. The extracellular portions of the different LIR proteins contain different numbers of Ig-like domains for example, four in the case of LILRB1, and LILRB2, and two in the case of LILRB4 (also known as LIR-5). The activating natural cytotoxicity receptor NKp46 is expressed in natural killer cells, and is organized as an extracellular portion having two Ig-like extracellular domains, a transmembrane domain, and a small cytoplasmic portion. GPVI, which also contains two Ig-like domains, participates in the processes of collagen-mediated platelet activation and arterial thrombus formation. Fc-alphaRI is expressed on monocytes, eosinophils, neutrophils, and macrophages; it mediates IgA-induced immune effector responses such as phagocytosis, antibody-dependent cell-mediated cytotoxicity and respiratory burst. Killer cell immunoglobulin-like receptors (KIRs; also known as CD158 for human KIR) are transmembrane glycoproteins expressed by natural killer cells and subsets of T cells. KIRs are a family of highly polymorphic activating and inhibitory receptors that serve as key regulators of human NK cell function. The KIR proteins are classified by the number of extracellular immunoglobulin domains (2D or 3D) and by whether they have a long (L) or short (S) cytoplasmic domain. KIR proteins with the long cytoplasmic domain transduce inhibitory signals upon ligand binding via an immune tyrosine-based inhibitory motif (ITIM), while KIR proteins with the short cytoplasmic domain lack the ITIM motif and instead associate with the TYRO protein tyrosine kinase binding protein to transduce activating signals. The major ligands for KIR are MHC class I (HLA-A, -B or -C) molecules.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 530364648 121 PPVLSAIPSPEPREGSLVTLRCQTklhPLRSAlrlLFSFHKDGHTLQDRGPHP-------ELCIPGAKEGDSGLYWC 190
Cdd:cd16843    1 KPFLSAEPSSVVPLGENVTIRCQG---PPEAV---LFQLYKEGNSLSQGTVREkepqnkaEFYIPHMDRNHAGRYRC 71

Second immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs), and similar domains; The members here are composed of the second immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs). Interactions between IgG and FcgammaR are important to the initiation of cellular and humoral response. IgG binding to FcgammaR leads to a cascade of signals and ultimately to functions such as antibody-dependent-cellular-cytotoxicity (ADCC), endocytosis, phagocytosis, release of inflammatory mediators, etc. FcgammaR has two Ig-like domains. This group also contains FcepsilonRI which binds IgE with high affinity.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 530364648  29 WLYLQAWPNPVFEGDALTLRCQGWKNTPLSQVKFYRDGKFLHFSKENQTLSMGAATVQSRGQYSCSGQVMYipqtFTQTS 108
Cdd:cd05753    1 WLLLQAPSAVVFEGEPLTLRCHGWKDKKVHKVTYYKDGKALKFSYENSNFSIPQATLSDSGSYHCSGTVRI----KRRSS 76

                 ....*..
gi 530364648 109 ETAMVQV 115
Cdd:cd05753   77 ESVNITV 83

Immunoglobulin domain; This domain contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 530364648  216 RPVLTLHhgPADPAVGDMVQLLCEAQrGSPPILYSFYLDEKIVGNHsapcggtTSLLFPVKSEQDAGNYSCEAENSVSRE 295
Cdd:pfam13895   1 KPVLTPS--PTVVTEGEPVTLTCSAP-GNPPPSYTWYKDGSAISSS-------PNFFTLSVSAEDSGTYTCVARNGRGGK 70

                  ....
gi 530364648  296 RSEP 299
Cdd:pfam13895  71 VSNP 74

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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 530364648 234 VQLLCEAqRGSPPILYSFYLDEKIVGNHSAPC----GGTTSLLFPVKSEQDAGNYSCEAENSVSRERS 297
Cdd:cd00096    1 VTLTCSA-SGNPPPTITWYKNGKPLPPSSRDSrrseLGNGTLTISNVTLEDSGTYTCVASNSAGGSAS 67

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
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 530364648  230 VGDMVQLLCEAQRGSPPILYSF-----YLDEKIVGNHSAPCGGTTSLLFPVKSEQDAGNYSCEAENSVS 293
Cdd:pfam00047  10 EGDSATLTCSASTGSPGPDVTWskeggTLIESLKVKHDNGRTTQSSLLISNVTKEDAGTYTCVVNNPGG 78

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 530364648 229 AVGDMVQLLCEAQRGSPPILYSFYLDEK---IVGNHSAPCGGTTSLLFPVKSEqDAGNYSCEAENSVSRERSEPKKLS 303
Cdd:cd05724   10 AVGEMAVLECSPPRGHPEPTVSWRKDGQplnLDNERVRIVDDGNLLIAEARKS-DEGTYKCVATNMVGERESRAARLS 86

Immunoglobulin (Ig)-like domain of human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) domains 2, 4, and 6, and similar domains; The members here are composed of the second, fourth, and sixth immunoglobulin (Ig)-like domains in human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) protein subfamily. The CEA family is a group of anchored or secreted glycoproteins expressed by epithelial cells, leukocytes, endothelial cells, and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. This group represents the CEACAM subfamily. CEACAM1 has many important cellular functions; it is a cell adhesion molecule and a signaling molecule that regulates the growth of tumor cells, an angiogenic factor, and a receptor for bacterial and viral pathogens, including mouse hepatitis virus (MHV). In mice, four isoforms of CEACAM1 generated by alternative splicing have either two [D1, D4] or four [D1-D4] Ig-like domains on the cell surface.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 530364648 232 DMVQLLCEAQRGSPPILYSFyldekivGNHSAPC--------GGTTSLLFPVKSEqDAGNYSCEAENSVSRERSEPKKL 302
Cdd:cd05740   16 DAVTLTCEPETQNTSYLWWF-------NGQSLPVtprltlsnGNRTLTLLNVTRE-DAGAYQCEISNPVSANRSDPVTL 86

Immunoglobulin (Ig) constant domain of the complement receptor of the immunoglobulin superfamily (CRIg); The members here are composed of the Immunoglobulin (Ig) constant domain of the complement receptor of the immunoglobulin superfamily (CRIg). The N-terminal domain of CRIg (also referred to 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. CRIg plays a role in the complement system, an 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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 530364648 231 GDMVQLLCEAQrGSPPILYSFYlDEKIVGNHSAPCGGTTSLLFPVKSEQDAGNYSCEAENSV-SRERSEPKKLSLK 305
Cdd:cd16082   13 GMRISLQCQAW-GSPPISYVWY-KEQTNNQEPIKVAALSTLLFKPAVVADSGSYFCTAKGRVgSEQRSDIVKFVVK 86

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 530364648  125 SAIPSPEPREGSLVTLRCqtKLHPLRSALRLLFSFHKDGHTLQDRGPHPE-------LCIPGAKEGDSGLYWCEVAPEGG 197
Cdd:pfam00047   1 SAPPTVTVLEGDSATLTC--SASTGSPGPDVTWSKEGGTLIESLKVKHDNgrttqssLLISNVTKEDAGTYTCVVNNPGG 78

                  ....
gi 530364648  198 QVQK 201
Cdd:pfam00047  79 SATL 82

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 530364648  122 PVLSAIPSP-EPREGSLVTLRCQTKLHPLRSalrllFSFHKDGHTLQD--------RGPHPELCIPGAKEGDSGLYWCEV 192
Cdd:pfam07679   1 PKFTQKPKDvEVQEGESARFTCTVTGTPDPE-----VSWFKDGQPLRSsdrfkvtyEGGTYTLTISNVQPDDSGKYTCVA 75

                          90
                  ....*....|....*.
gi 530364648  193 APEGGQVQKqSPQLEV 208
Cdd:pfam07679  76 TNSAGEAEA-SAELTV 90

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 530364648   39 VFEGDALTLRCQGwKNTPLSQVKFYRDGKFL--------HFSKENQTLSMGAATVQSRGQYSC 93
Cdd:pfam13927  13 VREGETVTLTCEA-TGSPPPTITWYKNGEPIssgstrsrSLSGSNSTLTISNVTRSDAGTYTC 74