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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 665394116   263 SKNVTALLGKTAYLNCRVKNLGNktmlLQVSWVRHRDIHLLTVGRYTYTSDqrfraihqpqTEDWMLQIKYPQHRDSGIY 342
Cdd:smart00410   1 PPSVTVKEGESVTLSCEASGSPP----PEVTWYKQGGKLLAESGRFSVSRS----------GSTSTLTISNVTPEDSGTY 66

                           90
                   ....*....|....*....
gi 665394116   343 ECQVSTTPHM-SHYIHLNV 360
Cdd:smart00410  67 TCAATNSSGSaSSGTTLTV 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 665394116   263 SKNVTALLGKTAYLNCRVKNLGNktmlLQVSWVRHRDIHLLTVGRYTYTSDqrfraihqpqTEDWMLQIKYPQHRDSGIY 342
Cdd:smart00410   1 PPSVTVKEGESVTLSCEASGSPP----PEVTWYKQGGKLLAESGRFSVSRS----------GSTSTLTISNVTPEDSGTY 66

                           90
                   ....*....|....*....
gi 665394116   343 ECQVSTTPHM-SHYIHLNV 360
Cdd:smart00410  67 TCAATNSSGSaSSGTTLTV 85

Immunoglobulin (Ig)-like domain of the human basement membrane heparan sulfate proteoglycan perlecan and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain of the human basement membrane heparan sulfate proteoglycan perlecan, also known as HSPG2, and similar proteins. Perlecan consists of five domains: domain I has three putative heparan sulfate attachment sites, domain II has four LDL receptor-like repeats, and one Ig-like repeat, domain III resembles the short arm of laminin chains, domain IV has multiple Ig-like repeats (21 repeats in human perlecan), and domain V resembles the globular G domain of the laminin A chain and internal repeats of EGF. Perlecan may participate in a variety of biological functions including cell binding, LDL-metabolism, basement membrane assembly and selective permeability, calcium binding, and growth- and neurite-promoting activities.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 665394116 378 GSTINLTCIIQNSPEPpaYIFWNHN-NAFPSHPQIInydsprggvsvVTNKGDTTTsfLLIKSARPSDSGHYQCNPSNAK 456
Cdd:cd05743    1 GETVEFTCVATGVPTP--IINWRLNwGHVPDSARVS-----------ITSEGGYGT--LTIRDVKESDQGAYTCEAINTR 65

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 665394116 266 VTALLGKTAYLNCRVKNLGNKTmllQVSWVRHRD--------IHLLTVGRYTYTSDQRFRAIHQPQTeDWMLQIKYPQHR 337
Cdd:cd00099    8 LSVQEGESVTLSCEVSSSFSST---YIYWYRQKPgqgpefliYLSSSKGKTKGGVPGRFSGSRDGTS-SFSLTISNLQPE 83

                         90
                 ....*....|....*....
gi 665394116 338 DSGIYECQVSTTPHMSHYI 356
Cdd:cd00099   84 DSGTYYCAVSESGGTDKLT 102

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 665394116   263 SKNVTALLGKTAYLNCRVKNLGNktmlLQVSWVRHRDIHLLTVGRYTYTSDqrfraihqpqTEDWMLQIKYPQHRDSGIY 342
Cdd:smart00410   1 PPSVTVKEGESVTLSCEASGSPP----PEVTWYKQGGKLLAESGRFSVSRS----------GSTSTLTISNVTPEDSGTY 66

                           90
                   ....*....|....*....
gi 665394116   343 ECQVSTTPHM-SHYIHLNV 360
Cdd:smart00410  67 TCAATNSSGSaSSGTTLTV 85

Immunoglobulin (Ig)-like domain of the human basement membrane heparan sulfate proteoglycan perlecan and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain of the human basement membrane heparan sulfate proteoglycan perlecan, also known as HSPG2, and similar proteins. Perlecan consists of five domains: domain I has three putative heparan sulfate attachment sites, domain II has four LDL receptor-like repeats, and one Ig-like repeat, domain III resembles the short arm of laminin chains, domain IV has multiple Ig-like repeats (21 repeats in human perlecan), and domain V resembles the globular G domain of the laminin A chain and internal repeats of EGF. Perlecan may participate in a variety of biological functions including cell binding, LDL-metabolism, basement membrane assembly and selective permeability, calcium binding, and growth- and neurite-promoting activities.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 665394116 378 GSTINLTCIIQNSPEPpaYIFWNHN-NAFPSHPQIInydsprggvsvVTNKGDTTTsfLLIKSARPSDSGHYQCNPSNAK 456
Cdd:cd05743    1 GETVEFTCVATGVPTP--IINWRLNwGHVPDSARVS-----------ITSEGGYGT--LTIRDVKESDQGAYTCEAINTR 65

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 665394116 378 GSTINLTCIIQNSPePPAYIFWNHNNAfPSHPQ-IINYDSPRGGVSVVTNKG------DTTTSFLLIKSARPSDSGHYQC 450
Cdd:cd00099   13 GESVTLSCEVSSSF-SSTYIYWYRQKP-GQGPEfLIYLSSSKGKTKGGVPGRfsgsrdGTSSFSLTISNLQPEDSGTYYC 90

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 665394116  378 GSTINLTCIIQNSPEPPayIFWNHNNafpshpQIINyDSPRGgvsVVTNKGDTTTsfLLIKSARPSDSGHYQC---NPSN 454
Cdd:pfam07679  15 GESARFTCTVTGTPDPE--VSWFKDG------QPLR-SSDRF---KVTYEGGTYT--LTISNVQPDDSGKYTCvatNSAG 80

                          90
                  ....*....|
gi 665394116  455 AKPKSVTVHV 464
Cdd:pfam07679  81 EAEASAELTV 90

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 665394116  368 IGAPDLYIESGSTINLTCIIqNSPEPPAYIFWNHNNafpshpqiinyDSPRGGVSVVTNKGDTTTSFLLIKSARPSDSGH 447
Cdd:pfam00047   1 SAPPTVTVLEGDSATLTCSA-STGSPGPDVTWSKEG-----------GTLIESLKVKHDNGRTTQSSLLISNVTKEDAGT 68

                          90
                  ....*....|....*...
gi 665394116  448 YQC---NPSNAKPKSVTV 462
Cdd:pfam00047  69 YTCvvnNPGGSATLSTSL 86

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 665394116  256 PYFDKaFSKNVTALLGKTAYLNCRVKnlGNKTMllQVSWvRHRDIHLLTVGRYtytsdqRFRAIHQPQTedwmLQIKYPQ 335
Cdd:pfam07679   1 PKFTQ-KPKDVEVQEGESARFTCTVT--GTPDP--EVSW-FKDGQPLRSSDRF------KVTYEGGTYT----LTISNVQ 64

                          90
                  ....*....|..
gi 665394116  336 HRDSGIYECQVS 347
Cdd:pfam07679  65 PDDSGKYTCVAT 76

agrin-responsive first immunoglobulin-like domains (Ig1) of the MuSK ectodomain; a member of the I-set of IgSF domains; The members here are composed of the first immunoglobulin-like domains (Ig1) of the Muscle-specific kinase (MuSK). MuSK is a receptor tyrosine kinase specifically expressed in skeletal muscle, where it plays a central role in the formation and maintenance of the neuromuscular junction (NMJ). MuSK is activated by agrin, a neuron-derived heparan sulfate proteoglycan. The activation of MUSK in myotubes regulates the formation of NMJs through the regulation of different processes including the specific expression of genes in subsynaptic nuclei, the reorganization of the actin cytoskeleton and the clustering of the acetylcholine receptors (AChR) in the postsynaptic membrane. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. 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 structure of the MuSK lacks this strand and thus it belongs to the I-set of the IgSF. 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 hemolymph protein hemolin, 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        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 665394116 372 DLYIESGSTINLTCIIQNSPEPPayIFWNHNNAfpshpQIINYDSprgGVSVVTNkGDTttsfLLIKSARPSDSGHYQCN 451
Cdd:cd20970   11 TVTAREGENATFMCRAEGSPEPE--ISWTRNGN-----LIIEFNT---RYIVREN-GTT----LTIRNIRRSDMGIYLCI 75

                 ....*....
gi 665394116 452 PSNAKPKSV 460
Cdd:cd20970   76 ASNGVPGSV 84

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        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 665394116 256 PYFDKAFSKNVTALLGKTAYLNCRVKNLGNKTmllqVSWVrHRDIHLltvgrytytSDQRFRAihqpQTEDWMLQIKYPQ 335
Cdd:cd20978    1 PKFIQKPEKNVVVKGGQDVTLPCQVTGVPQPK----ITWL-HNGKPL---------QGPMERA----TVEDGTLTIINVQ 62

                 ....*....
gi 665394116 336 HRDSGIYEC 344
Cdd:cd20978   63 PEDTGYYGC 71

First immunoglobulin variable (IgV) domain of poliovirus receptor (PVR, also known as CD155 and necl-5), and similar domains; The members here are composed of the first immunoglobulin (Ig) domain of poliovirus receptor (PVR, also known as CD155 and nectin-like protein 5 (necl-5)). Poliovirus (PV) binds to its cellular receptor (PVR/CD155) to initiate infection. CD155 is a membrane-anchored, single-span glycoprotein; its extracellular region has three Ig-like domains. There are four different isotypes of CD155 (referred to as alpha, beta, gamma, and delta), that result from alternate splicing of the CD155 mRNA, and have identical extracellular domains. CD155-beta and CD155-gamma are secreted; CD155-alpha and CD155-delta are membrane-bound and function as PV receptors. The virus recognition site is contained in the amino-terminal domain, D1. Having the virus attachment site on the receptor distal from the plasma membrane may be important for successful initiation of infection of cells by the virus. CD155 binds in the poliovirus "canyon" with a footprint similar to that of the intercellular adhesion molecule-1 receptor on human rhinoviruses. This group also includes the first Ig-like domain of nectin-1 (also known as poliovirus receptor related protein(PVRL)1; CD111), nectin-3 (also known as PVRL 3), nectin-4 (also known as PVRL4; LNIR receptor)and DNAX accessory molecule 1 (DNAM-1; CD226).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 665394116 265 NVTALLGKTAYLNCRVKNLGNKTmLLQVSWVRHRDIHLLTVGRY----------TYTSDQRFRAiHQPQTEDWMLQIKYP 334
Cdd:cd05718    8 EVTGFLGGSVTLPCSLTSPGTTK-ITQVTWMKIGAGSSQNVAVFhpqygpsvpnPYAERVEFLA-ARLGLRNATLRIRNL 85

                         90
                 ....*....|....*.
gi 665394116 335 QHRDSGIYECQVSTTP 350
Cdd:cd05718   86 RVEDEGNYICEFATFP 101