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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 16506255    188 PSSEPQEGGSVTLSCQTK------LALQRSASRLLFsfYKDGRSLSVRGVSSELKIPKASEEHSGSYWCEAVTEDRQISK 261
Cdd:smart00410   2 PSVTVKEGESVTLSCEASgspppeVTWYKQGGKLLA--ESGRFSVSRSGSTSTLTISNVTPEDSGTYTCAATNSSGSASS 79

Immunoglobulin domain; This domain contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 16506255    89 WLILQGPATLIFEGDTLVLHCRAWqDWPLTQVIFYREGSALgppGPKSEFSITMVQKSDGGHYHCSGifrSPGPGSrEAA 168
Cdd:pfam13895   1 KPVLTPSPTVVTEGEPVTLTCSAP-GNPPPSYTWYKDGSAI---SSSPNFFTLSVSAEDSGTYTCVA---RNGRGG-KVS 72

                  ....*..
gi 16506255   169 SPVAITV 175
Cdd:pfam13895  73 NPVELTV 79

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 16506255   182 PVLKALPSS-EPQEGGSVTLSCQTklalqRSASRLLFSFYKDG--------RSLSVRGVSSELKIPKASEEHSGSYWCEA 252
Cdd:pfam13927   2 PVITVSPSSvTVREGETVTLTCEA-----TGSPPPTITWYKNGepissgstRSRSLSGSNSTLTISNVTRSDAGTYTCVA 76

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

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 16506255    101 EGDTLVLHCRAWQDwPLTQVIFYREGsaLGPPGPKSEFSITM-----------VQKSDGGHYHC 153
Cdd:smart00410   8 EGESVTLSCEASGS-PPPEVTWYKQG--GKLLAESGRFSVSRsgststltisnVTPEDSGTYTC 68

Immunoglobulin domain; This domain contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 16506255    89 WLILQGPATLIFEGDTLVLHCRAWqDWPLTQVIFYREGSALgppGPKSEFSITMVQKSDGGHYHCSGifrSPGPGSrEAA 168
Cdd:pfam13895   1 KPVLTPSPTVVTEGEPVTLTCSAP-GNPPPSYTWYKDGSAI---SSSPNFFTLSVSAEDSGTYTCVA---RNGRGG-KVS 72

                  ....*..
gi 16506255   169 SPVAITV 175
Cdd:pfam13895  73 NPVELTV 79

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 16506255   182 PVLKALPSS-EPQEGGSVTLSCQTklalqRSASRLLFSFYKDG--------RSLSVRGVSSELKIPKASEEHSGSYWCEA 252
Cdd:pfam13927   2 PVITVSPSSvTVREGETVTLTCEA-----TGSPPPTITWYKNGepissgstRSRSLSGSNSTLTISNVTRSDAGTYTCVA 76

Immunoglobulin (Ig)-like domain in neuregulins; The members here are composed of the immunoglobulin (Ig)-like domain in neuregulins (NRGs). NRGs are signaling molecules which participate in cell-cell interactions in the nervous system, breast, heart, and other organ systems, and are implicated in the pathology of diseases including schizophrenia, multiple sclerosis, and breast cancer. There are four members of the neuregulin gene family (NRG-1, NRG-2, NRG-3, and NRG-4). The NRG-1 protein, binds to and activates the tyrosine kinases receptors ErbB3 and ErbB4, initiating signaling cascades. The other NRGs proteins bind one or the other or both of these ErbBs. NRG-1 has multiple functions: in the brain it regulates various processes such as radial glia formation and neuronal migration, dendritic development, and expression of neurotransmitters receptors, while in the peripheral nervous system NRG-1 regulates processes such as target cell differentiation, and Schwann cell survival. There are many NRG-1 isoforms which arise from the alternative splicing of mRNA. Less is known of the functions of the other NRGs. NRG-2 and NRG-3 are expressed predominantly in the nervous system. NRG-2 is expressed by motor neurons and terminal Schwann cells, and is concentrated near synaptic sites and may be a signal that regulates synaptic differentiation. NRG-4 has been shown to direct pancreatic islet cell development towards the delta-cell lineage.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 16506255 182 PVLKALPSSEPQEGGSVTLSCQTKlalqRSASRLLFSFYKDGRSLS--------VRGV--SSELKIPKASEEHSGSYWCE 251
Cdd:cd05750   1 PKLKEMKSQTVQEGSKLVLKCEAT----SENPSPRYRWFKDGKELNrkrpknikIRNKkkNSELQINKAKLEDSGEYTCV 76

                .
gi 16506255 252 A 252
Cdd:cd05750  77 V 77

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
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 16506255 182 PVLKALPSSEPQEGGSVTLSCQTKLALQRsasrllFSFYKDGRSLS----VRGVSSELKIPKASEEHSGSYWC 250
Cdd:cd05711   2 PFLSAHPGPVVPSGENVTLQCHSRIGFDR------FILYKEGRSPLlqfhGSGFQASFPLGPVTPAHAGTYRC 68

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 16506255 198 VTLSCQTklalqRSASRLLFSFYKDGRSL--------SVRGVSSELKIPKASEEHSGSYWCEA 252
Cdd:cd00096   1 VTLTCSA-----SGNPPPTITWYKNGKPLppssrdsrRSELGNGTLTISNVTLEDSGTYTCVA 58

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

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 16506255    101 EGDTLVLHCRAWQDwPLTQVIFYREGsaLGPPGPKSEFSITM-----------VQKSDGGHYHC 153
Cdd:smart00410   8 EGESVTLSCEASGS-PPPEVTWYKQG--GKLLAESGRFSVSRsgststltisnVTPEDSGTYTC 68