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 15826520  87 WLLLQASAEVVMEGQPLFLRCHGWRNWDVYKVIYYKDGEALKYWYENHNISITNATVEDSGTYYCTGKVWQLDYESEPLN 166
Cdd:cd05753   1 WLLLQAPSAVVFEGEPLTLRCHGWKDKKVHKVTYYKDGKALKFSYENSNFSIPQATLSDSGSYHCSGTVRIKRRSSESVN 80

                ...
gi 15826520 167 ITV 169
Cdd:cd05753  81 ITV 83

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 15826520  87 WLLLQASAEVVMEGQPLFLRCHGWRNWDVYKVIYYKDGEALKYWYENHNISITNATVEDSGTYYCTGKVWQLDYESEPLN 166
Cdd:cd05753   1 WLLLQAPSAVVFEGEPLTLRCHGWKDKKVHKVTYYKDGKALKFSYENSNFSIPQATLSDSGSYHCSGTVRIKRRSSESVN 80

                ...
gi 15826520 167 ITV 169
Cdd:cd05753  81 ITV 83

Immunoglobulin domain; This domain contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 15826520    87 WLLLQASAEVVMEGQPLFLRCHGWRNwDVYKVIYYKDGEALKywyENHNISITNATVEDSGTYYCTGKVWQLDYESEPLN 166
Cdd:pfam13895   1 KPVLTPSPTVVTEGEPVTLTCSAPGN-PPPSYTWYKDGSAIS---SSPNFFTLSVSAEDSGTYTCVARNGRGGKVSNPVE 76

                  ...
gi 15826520   167 ITV 169
Cdd:pfam13895  77 LTV 79

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 15826520     96 VVMEGQPLFLRCHGWRN--------WDVYKVIYYKDGEALKYWYENHNISITNATVEDSGTYYCTGKVWQLDYESEpLNI 167
Cdd:smart00410   5 TVKEGESVTLSCEASGSpppevtwyKQGGKLLAESGRFSVSRSGSTSTLTISNVTPEDSGTYTCAATNSSGSASSG-TTL 83

                   ..
gi 15826520    168 TV 169
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 15826520  87 WLLLQASAEVVMEGQPLFLRCHGWRNWDVYKVIYYKDGEALKYWYENHNISITNATVEDSGTYYCTGKVWQLDYESEPLN 166
Cdd:cd05753   1 WLLLQAPSAVVFEGEPLTLRCHGWKDKKVHKVTYYKDGKALKFSYENSNFSIPQATLSDSGSYHCSGTVRIKRRSSESVN 80

                ...
gi 15826520 167 ITV 169
Cdd:cd05753  81 ITV 83

Immunoglobulin domain; This domain contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 15826520    87 WLLLQASAEVVMEGQPLFLRCHGWRNwDVYKVIYYKDGEALKywyENHNISITNATVEDSGTYYCTGKVWQLDYESEPLN 166
Cdd:pfam13895   1 KPVLTPSPTVVTEGEPVTLTCSAPGN-PPPSYTWYKDGSAIS---SSPNFFTLSVSAEDSGTYTCVARNGRGGKVSNPVE 76

                  ...
gi 15826520   167 ITV 169
Cdd:pfam13895  77 LTV 79

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 15826520     96 VVMEGQPLFLRCHGWRN--------WDVYKVIYYKDGEALKYWYENHNISITNATVEDSGTYYCTGKVWQLDYESEpLNI 167
Cdd:smart00410   5 TVKEGESVTLSCEASGSpppevtwyKQGGKLLAESGRFSVSRSGSTSTLTISNVTPEDSGTYTCAATNSSGSASSG-TTL 83

                   ..
gi 15826520    168 TV 169
Cdd:smart00410  84 TV 85

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

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 15826520     19 GENVTLTCNGNNFfEVSSTKWFHNG-----------SLSEETNSSLNIVNAKFEDSGEYKCQ--HQQVNESEPVYLEV 83
Cdd:smart00410   9 GESVTLSCEASGS-PPPEVTWYKQGgkllaesgrfsVSRSGSTSTLTISNVTPEDSGTYTCAatNSSGSASSGTTLTV 85

Second 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 second immunoglobulin (Ig)-like domain 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        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 15826520  96 VVMEGQPLFLRCHGWRNWDVYKViyYKDGEALKYWYENH----NISITNATVEDSGTYYCTGKVWQLDYE----SEPLNI 167
Cdd:cd05711  11 VVPSGENVTLQCHSRIGFDRFIL--YKEGRSPLLQFHGSgfqaSFPLGPVTPAHAGTYRCYGSYNHSPYEwsapSDPLEI 88

                ..
gi 15826520 168 TV 169
Cdd:cd05711  89 VV 90

Sixth immunoglobulin (Ig) domain of contactin; The members here are composed of the sixth 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 15826520   6 KVSLNPPWNRIFKGENVTLTCNG--NNFFEVSSTkWFHNG---SLSE-----------ETNSSLNIVNAKFEDSGEYKCQ 69
Cdd:cd04970   4 RITLAPSNADITVGENATLQCHAshDPTLDLTFT-WSFNGvpiDLEKieghyrrrygkDSNGDLEIVNAQLKHAGRYTCT 82

                        90       100       110
                ....*....|....*....|....*....|...
gi 15826520  70 HQQVNESepvylevfsdwllLQASAEVVMEGQP 102
Cdd:cd04970  83 AQTVVDS-------------DSASATLVVRGPP 102

Immunoglobulin domain; This domain contains immunoglobulin-like domains.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 15826520     6 KVSLNPPWNRIFKGENVTLTCNGNNfFEVSSTKWFHNGS-LSEETNSSLNIVNAkfEDSGEYKCQ 69
Cdd:pfam13895   1 KPVLTPSPTVVTEGEPVTLTCSAPG-NPPPSYTWYKDGSaISSSPNFFTLSVSA--EDSGTYTCV 62

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
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 15826520  19 GENVTLTCNGNNFFEVSSTKWFHN----------------------------GSLSEETNSSLNIVNAKFEDSGEYKCQ 69
Cdd:cd00099  13 GESVTLSCEVSSSFSSTYIYWYRQkpgqgpefliylssskgktkggvpgrfsGSRDGTSSFSLTISNLQPEDSGTYYCA 91

Sixth immunoglobulin (Ig) domain of contactin-2; The members here are composed of the sixth immunoglobulin (Ig) domain of the neural cell adhesion molecule contactin-2-like. Contactins are comprised of six Ig domains followed by four fibronectin type III (FnIII) domains anchored to the membrane by glycosylphosphatidylinositol. Contactin-2 (TAG-1, axonin-1) facilitates cell adhesion by homophilic binding between molecules in apposed membranes. It may play a part in the neuronal processes of neurite outgrowth, axon guidance and fasciculation, and neuronal migration. The first four Ig domains form the intermolecular binding fragment, which arranges as a compact U-shaped module by contacts between IG domains 1 and 4, and domains 2 and 3. 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-2 is also expressed in retinal amacrine cells (AC) in the developing chick retina, corresponding to the period of formation and maturation of AC processes.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 15826520   6 KVSLNPPWNRIFKGENVTLTCNGNNFFEVSST-KWFHNG--------------SLSEETNSSLNIVNAKFEDSGEYKCQH 70
Cdd:cd05854   4 KITLAPSSADINQGENLTLQCHASHDPTMDLTfTWSLDDfpidldkpnghyrrMEVKETIGDLVIVNAQLSHAGTYTCTA 83

                        90       100       110
                ....*....|....*....|....*....|..
gi 15826520  71 QQVNESEpvylevfsdwlllQASAEVVMEGQP 102
Cdd:cd05854  84 QTVVDSA-------------SASATLVVRGPP 102

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 15826520  96 VVMEGQPLFLRCHGWRNWDVYKVIYY--KDGEALK---YWYENHN---------------------ISITNATVEDSGTY 149
Cdd:cd00099   9 SVQEGESVTLSCEVSSSFSSTYIYWYrqKPGQGPEfliYLSSSKGktkggvpgrfsgsrdgtssfsLTISNLQPEDSGTY 88

                        90
                ....*....|..
gi 15826520 150 YCTGKVWQLDYE 161
Cdd:cd00099  89 YCAVSESGGTDK 100

Fourth immunoglobulin (Ig)-like domain of hemolin, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the fourth immunoglobulin (Ig)-like domain of hemolin and similar proteins. Hemolin, an insect immunoglobulin superfamily (IgSF) member containing four Ig-like domains, is a lipopolysaccharide-binding immune protein induced during bacterial infection. Hemolin shares significant sequence similarity with the first four Ig-like domains of the transmembrane cell adhesion molecules (CAMs) of the L1 family. 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 fourth Ig-like domain of hemolin 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 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 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
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 15826520   5 PKVSLNPPWNRIFK-GENVTLTCngnnffEVSST-----KWFHNGS-LSEE------TNSSLNIVNAKFEDSGEYKC 68
Cdd:cd20978   1 PKFIQKPEKNVVVKgGQDVTLPC------QVTGVpqpkiTWLHNGKpLQGPmeratvEDGTLTIINVQPEDTGYYGC 71

Immunoglobulin (Ig)-like domain of platelet-derived growth factor (PDGF) receptors (R), alpha and beta; member of the I-set of IgSF domains; The members here are composed of the immunoglobulin (Ig)-like domain of platelet-derived growth factor (PDGF) receptors (R), alpha (also known as cluster of differentiation (CD) 140a), and beta (also known as CD140b). PDGF is a potent mitogen for connective tissue cells. PDGF-stimulated processes are mediated by three different PDGFs (PDGF-A,PDGF-B, and PDGF-C). PDGFRalpha binds to all three PDGFs, whereas the PDGFRbeta binds only to PDGF-B. PDGFRs alpha and beta have similar organization: an extracellular component with five Ig-like domains, a transmembrane segment, and a cytoplasmic portion having protein tyrosine kinase activity. In mice, PDGFRalpha and PDGFRbeta are essential for normal development.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 15826520   7 VSLNPPWNRIFKGENVTLTCN--GNnffEVSSTKWFHNGSLS-------EETN-------SSLNIVNAKFEDSGEYKC 68
Cdd:cd05861   5 VEMEAVKTVVRQGETITLMCIviGN---EVVDLEWTYPGKESgrgiepvEEFKvppyhlvYTLTIPSATLEDSGTYEC 79

Immunoglobulin I-set domain;

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 15826520    96 VVMEGQPLFLRCHGWRNWDVyKVIYYKDGEALK--------YWYENHNISITNATVEDSGTYYCT 152
Cdd:pfam07679  11 EVQEGESARFTCTVTGTPDP-EVSWFKDGQPLRssdrfkvtYEGGTYTLTISNVQPDDSGKYTCV 74