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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 38372921     19 SSEHINEGETAMLVCKSESVPPVTDWaWYKitdseDKALMNGSESRFFVSSSQGRSELHIENLNMEaDPGQYRCNGTSSK 98
Cdd:smart00410   2 PSVTVKEGESVTLSCEASGSPPPEVT-WYK-----QGGKLLAESGRFSVSRSGSTSTLTISNVTPE-DSGTYTCAATNSS 74

                           90
                   ....*....|.
gi 38372921     99 GSDQAIITLRV 109
Cdd:smart00410  75 GSASSGTTLTV 85

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 38372921     19 SSEHINEGETAMLVCKSESVPPVTDWaWYKitdseDKALMNGSESRFFVSSSQGRSELHIENLNMEaDPGQYRCNGTSSK 98
Cdd:smart00410   2 PSVTVKEGESVTLSCEASGSPPPEVT-WYK-----QGGKLLAESGRFSVSRSGSTSTLTISNVTPE-DSGTYTCAATNSS 74

                           90
                   ....*....|.
gi 38372921     99 GSDQAIITLRV 109
Cdd:smart00410  75 GSASSGTTLTV 85

Fifth immunoglobulin (Ig)-like domain of Kirrel (kin of irregular chiasm-like) 3, and similar domains; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the fifth immunoglobulin (Ig)-like domain of Kirrel (kin of irregular chiasm-like) 3 (also known as Neph2). This protein has five Ig-like domains, one transmembrane domain, and a cytoplasmic tail. Included in this group is mammalian Kirrel (also known as Neph1), Kirrel2 (also known as Neph3), and Drosophila RST (also known as irregular chiasm C-roughest) protein. These proteins contain multiple Ig domains, have properties of cell adhesion molecules, and are important in organ development.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 38372921  10 GPPRVKAVKSSEHInEGETAMLVCKSESVPPVTD--WAWykitdsEDKALMNGSESRFFV---SSSQGR-SELHIENLNM 83
Cdd:cd05758   1 GPPIITAEATQPAI-LGEKARLECLVFSSPPPDRivWSW------DEGFLESGSSGRFSVetfPTEPGViSVLHISGTQR 73

                        90       100
                ....*....|....*....|....*
gi 38372921  84 EADPGQYRCNGTSSKGSDQAIITLR 108
Cdd:cd05758  74 SDFQTSFNCSAWNRFGEGTAIVSLG 98

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 38372921     19 SSEHINEGETAMLVCKSESVPPVTDWaWYKitdseDKALMNGSESRFFVSSSQGRSELHIENLNMEaDPGQYRCNGTSSK 98
Cdd:smart00410   2 PSVTVKEGESVTLSCEASGSPPPEVT-WYK-----QGGKLLAESGRFSVSRSGSTSTLTISNVTPE-DSGTYTCAATNSS 74

                           90
                   ....*....|.
gi 38372921     99 GSDQAIITLRV 109
Cdd:smart00410  75 GSASSGTTLTV 85

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 38372921    23 INEGETAMLVCKSESVPP--VTdwaWYKitdsEDKALmnGSESRFFVSSSQGRSELHIENLNMEaDPGQYRCNGTSSKGS 100
Cdd:pfam07679  12 VQEGESARFTCTVTGTPDpeVS---WFK----DGQPL--RSSDRFKVTYEGGTYTLTISNVQPD-DSGKYTCVATNSAGE 81

                  ....*....
gi 38372921   101 DQAIITLRV 109
Cdd:pfam07679  82 AEASAELTV 90

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 38372921  19 SSEHINEGETAMLVCKSESVPPVTDWAWYK-----------ITDSEDKALMNGSESRFFVSSSQG-RSELHIENLNMEaD 86
Cdd:cd00099   6 RSLSVQEGESVTLSCEVSSSFSSTYIYWYRqkpgqgpefliYLSSSKGKTKGGVPGRFSGSRDGTsSFSLTISNLQPE-D 84

                        90
                ....*....|....*...
gi 38372921  87 PGQYRCNGTSSKGSDQAI 104
Cdd:cd00099  85 SGTYYCAVSESGGTDKLT 102

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 38372921  12 PRVKAVKSSEhINEGETAMLVCKSESVPPVTDWAWYKitdsEDKALMNGSESRFFVSSSQGRSELHIENLNMEaDPGQYR 91
Cdd:cd05750   1 PKLKEMKSQT-VQEGSKLVLKCEATSENPSPRYRWFK----DGKELNRKRPKNIKIRNKKKNSELQINKAKLE-DSGEYT 74

                        90
                ....*....|....*...
gi 38372921  92 CNGTSSKGSDQAIITLRV 109
Cdd:cd05750  75 CVVENILGKDTVTGNVTV 92

Third immunoglobulin (Ig)-like domain of the L1 cell adhesion molecule (CAM), and similar domains; The members here are composed of the third immunoglobulin (Ig)-like domain of the L1 cell adhesion molecule (CAM). L1 belongs to the L1 subfamily of cell adhesion molecules (CAMs) and is comprised of an extracellular region having six Ig-like domains and five fibronectin type III domains, a transmembrane region and an intracellular domain. L1 is primarily expressed in the nervous system and is involved in its development and function. L1 is associated with an X-linked recessive disorder, X-linked hydrocephalus, MASA syndrome, and spastic paraplegia type 1, that involves abnormalities of axonal growth. This group also contains the chicken neuron-glia cell adhesion molecule, Ng-CAM and human neurofascin.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 38372921  19 SSEHINEGETAMLVCKSESVPpvTDW-AWYKITDSedkaLMNGsesRFFVSSSQgrSELHIENLNmEADPGQYRCNGTSS 97
Cdd:cd05731   3 SSTMVLRGGVLLLECIAEGLP--TPDiRWIKLGGE----LPKG---RTKFENFN--KTLKIENVS-EADSGEYQCTASNT 70

                        90
                ....*....|...
gi 38372921  98 KGSDQAIITLRVR 110
Cdd:cd05731  71 MGSARHTISVTVE 83

First immunoglobulin (Ig)-like domain of neural cell adhesion molecule NCAM-1, and similar domains; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin (Ig)-like domain of neural cell adhesion molecule NCAM-1. NCAM-1 plays important roles in the development and regeneration of the central nervous system, in synaptogenesis and neural migration. NCAM mediates cell-cell and cell-substratum recognition and adhesion via homophilic (NCAM-NCAM) and heterophilic (NCAM-nonNCAM) interactions. NCAM is expressed as three major isoforms having different intracellular extensions. The extracellular portion of NCAM has five N-terminal Ig-like domains and two fibronectin type III domains. The double zipper adhesion complex model for NCAM homophilic binding involves the Ig1, Ig2, and Ig3 domains. By this model, Ig1 and Ig2 mediate dimerization of NCAM molecules situated on the same cell surface (cis interactions), and Ig3 domains mediate interactions between NCAM molecules expressed on the surface of opposing cells (trans interactions), through binding to the Ig1 and Ig2 domains. The adhesive ability of NCAM is modulated by the addition of polysialic acid chains to the fifth Ig-like domain. Also included in this group is NCAM-2 (also known as OCAM/mamFas II and RNCAM). NCAM-2 is differentially expressed in the developing and mature olfactory epithelium (OE). 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        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 38372921  13 RVKAVKSSEHINEGETAMLVCKSESVPPVTDWawykiTDSEDKALMNGSESRFFVSSSQGRSELHIENLNMEaDPGQYRC 92
Cdd:cd04977   2 QVKIIPSYAEISVGESKFFLCKVSGDAKNINW-----VSPNGEKVLTKHGNLKVVNHGSVLSSLTIYNANIN-DAGIYKC 75

                        90
                ....*....|....*...
gi 38372921  93 NGTSSKGSD-QAIITLRV 109
Cdd:cd04977  76 VATNGKGTEsEATVKLDI 93

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 38372921    23 INEGETAMLVCKSESVPPVTDWAWYKitdsEDKALMNGSESrFFVSSSQGRSELHIENLNMEaDPGQYRCNGTSSKGSDQ 102
Cdd:pfam00047   8 VLEGDSATLTCSASTGSPGPDVTWSK----EGGTLIESLKV-KHDNGRTTQSSLLISNVTKE-DAGTYTCVVNNPGGSAT 81

                  ....*
gi 38372921   103 AIITL 107
Cdd:pfam00047  82 LSTSL 86