seven-transmembrane G protein-coupled receptor superfamily; This hierarchical evolutionary model represents the seven-transmembrane (7TM) receptors, often referred to as G protein-coupled receptors (GPCRs), which transmit physiological signals from the outside of the cell to the inside via G proteins. GPCRs constitute the largest known superfamily of transmembrane receptors across the three kingdoms of life that respond to a wide variety of extracellular stimuli including peptides, lipids, neurotransmitters, amino acids, hormones, and sensory stimuli such as light, smell and taste. All GPCRs share a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes. However, some 7TM receptors, such as the type 1 microbial rhodopsins, do not activate G proteins. Based on sequence similarity, GPCRs can be divided into six major classes: class A (the rhodopsin-like family), class B (the Methuselah-like, adhesion and secretin-like receptor family), class C (the metabotropic glutamate receptor family), class D (the fungal mating pheromone receptors), class E (the cAMP receptor family), and class F (the frizzled/smoothened receptor family). Nearly 800 human GPCR genes have been identified and are involved essentially in all major physiological processes. Approximately 40% of clinically marketed drugs mediate their effects through modulation of GPCR function for the treatment of a variety of human diseases including bacterial infections.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371  929 AGSPSVPLVIGCAVSCMALLTLLAIYAAFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFL 1008
Cdd:cd15988     1 TGSPSVPLMIGCAVSCMALLILLAIYAAFWRFIRSERSIILLNFCLSILASNILILVGQSQTLSKGVCTMTAAFLHFFFL 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1009 SSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTSSYCWLSLEGGLLYAFVGPAAVIV 1088
Cdd:cd15988    81 SSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTASYCWLSLEGGLLYAFVGPAAVIV 160

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1089 LVNMLIGIIVFNKLMARDGISDKSKKQRAG---------------------------------ASLWSSCVVLPLLALTW 1135
Cdd:cd15988   161 LVNMLIGIIVFNKLMSRDGISDKSKKQRAGseaepcsslllkcskcgvvssaamssatassamASLWSSCVVLPLLALTW 240

                         250       260       270       280       290
                  ....*....|....*....|....*....|....*....|....*....|.
gi 661567371 1136 MSAVLAMTDRRSVLFQALFAVFNSAQGFVITAVHCFLRREVQDVVKCQMGV 1186
Cdd:cd15988   241 MSAVLAMTDRRSILFQVLFAVFNSVQGFVIITVHCFLRREVQDVVKCQMGG 291

GPCR-Autoproteolysis INducing (GAIN) domain; The GAIN a domain of alpha-helices and beta-strands that is found in cell-adhesion GPCRs and precedes the GPS motif where the autoproteolysis occurs, family, pfam01825. The full GAIN domain, comprises the GPS and the GAIN, in cell-adhesion GPCRs, and is the functional unit for autoproteolysis. The GPS motif at the end of the GAIN domain is an ancient domain that exists in primitive ancestor organizms, and the full GAIN + GPS is conserved in all cell-adhesion GPCRs and all PKD1-related proteins.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371   614 GMSQVVRSLQELLARRTYYSGDLLFSVDILRNVTDTFKRATYVPSADDVQRFFQVVSFMVDAENKEKWDDAQQVSPGSVH 693
Cdd:pfam16489    1 GAKELARELRNATRHGPLYGGDVLTAVELLSQLFDLLATQDATLSNAFLENFVQTVSNLLDPENRESWEDLQQTERGTAA 80

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371   694 --LLRVVEDFIHLVGDALKAFQSSLIVTDNLVISIQRE--PVSAVSSDITFPMRGRRGmkdwvrHSEDRLFLPKEVLSLS 769
Cdd:pfam16489   81 tkLLRTLEEYALLLAQNMKYLTPFTIVTPNIVLSVDRLdtHNFKGARFPRFPMKGERP------KDEDSVKLPPKAFKPP 154

G-protein-coupled receptor proteolytic site domain; Present in latrophilin/CL-1, sea urchin REJ and polycystin.

                            10        20        30        40        50
                    ....*....|....*....|....*....|....*....|....*....|....
gi 661567371    870 TDPHCASWDYSRadassGDWDTENCQTLETQAAHTRCQCQHLSTFAVLAQPPKD 923
Cdd:smart00303    1 FNPICVFWDESS-----GEWSTRGCELLETNGTHTTCSCNHLTTFAVLMDVPPI 49

Thrombospondin type 1 repeats; Type 1 repeats in thrombospondin-1 bind and activate TGF-beta.

                            10        20        30        40        50
                    ....*....|....*....|....*....|....*....|....*....|...
gi 661567371    478 WGPWNAWSLCSKTCDTGWQRRFRMC--QATGTQGYPCEGTGEEVKPCSEKRCP 528
Cdd:smart00209    1 WSEWSEWSPCSVTCGGGVQTRTRSCcsPPPQNGGGPCTGEDVETRACNEQPCP 53

Domain present in hormone receptors;

                            10        20        30        40        50        60        70
                    ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 661567371    531 HEMCRDEYVMLMTWKKAAAGEIIYNKCPPNASG-----SASRRCLLSAQgvayWGL--PSFARCISHEYRYL 595
Cdd:smart00008    2 DLGCPATWDGIICWPQTPAGQLVEVPCPKYFSGfsyktGASRNCTENGG----WSPpfPNYSNCTSNDYEEL 69

brain-specific angiogenesis inhibitor 2, a group VII adhesion GPCR, member of the class B2 family of seven-transmembrane G protein-coupled receptors; Brain-specific angiogenesis inhibitors (BAI1-3) constitute the group VII of cell-adhesion receptors that have been implicated in vascularization of glioblastomas. They belong to the B2 subfamily of class B GPCRs, are predominantly expressed in the brain, and are only present in vertebrates. Three BAIs, like all adhesion receptors, are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. For example, BAI1 N-terminus contain an integrin-binding RGD (Arg-Gly-Asp) motif in addition to five thrombospondin type 1 repeats (TSRs), which are known to regulate the anti-angiogenic activity of thrombospondin-1, whereas BAI2 and BAI3 have four TSRs, but do not possess RGD motifs. The TSRs are functionally involved in cell attachment, activation of latent TGF-beta, inhibition of angiogenesis and endothelial cell migration. The TSRs of BAI1 mediates direct binding to phosphatidylserine, which enables both recognition and internalization of apoptotic cells by phagocytes. Thus, BAI1 functions as a phosphatidylserine receptor that forms a trimeric complex with ELMO and Dock180, leading to activation of Rac-GTPase which promotes the binding and phagocytosis of apoptotic cells. BAI3 can also interact with the ELMO-Dock180 complex to activate the Rac pathway and can also bind to secreted C1ql proteins of the C1Q complement family via its N-terminal TSRs. BAI3 and its ligands C1QL1 are highly expressed during synaptogenesis and are involved in synapse specificity. Moreover, BAI2 acts as a transcription repressor to regulate vascular endothelial growth factor (VEGF) expression through interaction with GA-binding protein gamma (GABP). The N-terminal extracellular domains of all three BAIs also contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain, which undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif to generate N- and C-terminal fragments (NTF and CTF), a putative hormone-binding domain (HBD), and multiple N-glycosylation sites. The C-terminus of each BAI subtype ends with a conserved Gln-Thr-Glu-Val (QTEV) motif known to interact with PDZ domain-containing proteins, but only BAI1 possesses a proline-rich region, which may be involved in protein-protein interactions.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371  929 AGSPSVPLVIGCAVSCMALLTLLAIYAAFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFL 1008
Cdd:cd15988     1 TGSPSVPLMIGCAVSCMALLILLAIYAAFWRFIRSERSIILLNFCLSILASNILILVGQSQTLSKGVCTMTAAFLHFFFL 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1009 SSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTSSYCWLSLEGGLLYAFVGPAAVIV 1088
Cdd:cd15988    81 SSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTASYCWLSLEGGLLYAFVGPAAVIV 160

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1089 LVNMLIGIIVFNKLMARDGISDKSKKQRAG---------------------------------ASLWSSCVVLPLLALTW 1135
Cdd:cd15988   161 LVNMLIGIIVFNKLMSRDGISDKSKKQRAGseaepcsslllkcskcgvvssaamssatassamASLWSSCVVLPLLALTW 240

                         250       260       270       280       290
                  ....*....|....*....|....*....|....*....|....*....|.
gi 661567371 1136 MSAVLAMTDRRSVLFQALFAVFNSAQGFVITAVHCFLRREVQDVVKCQMGV 1186
Cdd:cd15988   241 MSAVLAMTDRRSILFQVLFAVFNSVQGFVIITVHCFLRREVQDVVKCQMGG 291

7 transmembrane receptor (Secretin family); This family is known as Family B, the secretin-receptor family or family 2 of the G-protein-coupled receptors (GCPRs). They have been described in many animal species, but not in plants, fungi or prokaryotes. Three distinct sub-families are recognized. Subfamily B1 contains classical hormone receptors, such as receptors for secretin and glucagon, that are all involved in cAMP-mediated signalling pathways. Subfamily B2 contains receptors with long extracellular N-termini, such as the leukocyte cell-surface antigen CD97; calcium-independent receptors for latrotoxin, and brain-specific angiogenesis inhibitors amongst others. Subfamily B3 includes Methuselah and other Drosophila proteins. Other than the typical seven-transmembrane region, characteriztic structural features include an amino-terminal extracellular domain involved in ligand binding, and an intracellular loop (IC3) required for specific G-protein coupling.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371   929 AGSPSVPLVIGCAVSCMALLTLLAIYAAFwRFIKSERSIILLNFCLSILASNILILVGQSRVLSKG--------VCTMTA 1000
Cdd:pfam00002    1 ALSLKVIYTVGYSLSLVALLLAIAIFLLF-RKLHCTRNYIHLNLFASFILRALLFLVGDAVLFNKQdldhcswvGCKVVA 79

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371  1001 AFLHFFFLSSFCWVLTEAWQSYLA-VIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTrTKGYGTSSYCWLSLEGGLLYA 1079
Cdd:pfam00002   80 VFLHYFFLANFFWMLVEGLYLYTLlVEVFFSERKYFWWYLLIGWGVPALVVGIWAGVD-PKGYGEDDGCWLSNENGLWWI 158

                          170       180       190       200       210       220       230       240
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371  1080 FVGPAAVIVLVNMLIGIIVFNKLMARDGISDKSKKQRAGASLW--SSCVVLPLLALTWMSAVLAMTDRR--SVLFQALFA 1155
Cdd:pfam00002  159 IRGPILLIILVNFIIFINIVRILVQKLRETNMGKSDLKQYRRLakSTLLLLPLLGITWVFGLFAFNPENtlRVVFLYLFL 238

                          250
                   ....*....|
gi 661567371  1156 VFNSAQGFVI 1165
Cdd:pfam00002  239 ILNSFQGFFV 248

Thrombospondin type 1 repeats; Type 1 repeats in thrombospondin-1 bind and activate TGF-beta.

                            10        20        30        40        50
                    ....*....|....*....|....*....|....*....|....*....|...
gi 661567371    367 WEEWGSWSLCSRSCGRGSRSRMRTCV--PPQHGGKACEGPELQTKLCSMAACP 417
Cdd:smart00209    1 WSEWSEWSPCSVTCGGGVQTRTRSCCspPPQNGGGPCTGEDVETRACNEQPCP 53

GPCR proteolysis site, GPS, motif; The GPS motif is found in GPCRs, and is the site for auto-proteolysis, so is thus named, GPS. The GPS motif is a conserved sequence of ~40 amino acids containing canonical cysteine and tryptophan residues, and is the most highly conserved part of the domain. In most, if not all, cell-adhesion GPCRs these undergo autoproteolysis in the GPS between a conserved aliphatic residue (usually a leucine) and a threonine, serine, or cysteine residue. In higher eukaryotes this motif is found embedded in the C-terminal beta-stranded part of a GAIN domain - GPCR-Autoproteolysis INducing (GAIN). The GAIN-GPS domain adopts a fold in which the GPS motif, at the C-terminus, forms five beta-strands that are tightly integrated into the overall GAIN domain. The GPS motif, evolutionarily conserved from tetrahymena to mammals, is the only extracellular domain shared by all human cell-adhesion GPCRs and PKD proteins, and is the locus of multiple human disease mutations. The GAIN-GPS domain is both necessary and sufficient functionally for autoproteolysis, suggesting an autoproteolytic mechanism whereby the overall GAIN domain fine-tunes the chemical environment in the GPS to catalyze peptide bond hydrolysis. In the cell-adhesion GPCRs and PKD proteins, the GPS motif is always located at the end of their long N-terminal extracellular regions, immediately before the first transmembrane helix of the respective protein.

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*.
gi 661567371   872 PHCASWDYSraDASSGDWDTENCQTLETQAAHTRCQCQHLSTFAVL 917
Cdd:pfam01825    1 PQCVFWDFT--NSTTGRWSTEGCTTVSLNDTHTVCSCNHLTSFAVL 44

Spondin-like TSP1 domain; This entry represents a sub-type of TSP1 domains that have an alternative disulphide binding pattern compared to the canonical TSP1 domain.

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*....
gi 661567371   369 EWGSWSLCSRSCGRGSRSRMRT-CVPPQHGGKACeGPELQTKLCSMAAC 416
Cdd:pfam19028    5 EWSEWSECSVTCGGGVQTRTRTvIVEPQNGGRPC-PELLERRPCNLPPC 52

Thrombospondin type 1 repeats; Type 1 repeats in thrombospondin-1 bind and activate TGF-beta.

                            10        20        30        40        50
                    ....*....|....*....|....*....|....*....|....*....|...
gi 661567371    422 WLEWGPWGPCSTSCANGTQQRSRKCSVAGPAW--ATCTGALTDTRECSNLECP 472
Cdd:smart00209    1 WSEWSEWSPCSVTCGGGVQTRTRSCCSPPPQNggGPCTGEDVETRACNEQPCP 53

Thrombospondin type 1 domain;

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*...
gi 661567371   424 EWGPWGPCSTSCANGTQQRSRKCSVAGPAWATCTGALTDTRECSNLEC 471
Cdd:pfam00090    2 PWSPWSPCSVTCGKGIQVRQRTCKSPFPGGEPCTGDDIETQACKMDKC 49

Thrombospondin type 1 domain;

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*....
gi 661567371   479 GPWNAWSLCSKTCDTGWQRRFRMCQATGTQGYPCEGTGEEVKPCSEKRC 527
Cdd:pfam00090    1 SPWSPWSPCSVTCGKGIQVRQRTCKSPFPGGEPCTGDDIETQACKMDKC 49

sporozoite surface protein 2 (SSP2); Provisional

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 661567371  359 ATCpvhGVWEEWgswSLCSRSCGRGSRSRMRtcvPPQHGGkaCEgPELQTKlCSMAACPVE 419
Cdd:PTZ00441  238 ASC---GPWDEW---TPCSVTCGKGTHSRSR---PILHEG--CT-THMVEE-CEEEECPVE 285

Hormone receptor domain; This extracellular domain contains four conserved cysteines that probably for disulphide bridges. The domain is found in a variety of hormone receptors. It may be a ligand binding domain.

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 661567371   531 HEMCRDEYVMLMTWKKAAAGEIIYNKCPPNAS-----GSASRRCLLSAQgvayWGLPS---FARCISH 590
Cdd:pfam02793    1 GLGCPRTWDGILCWPRTPAGETVEVPCPDYFSgfdprGNASRNCTEDGT----WSEHPpsnYSNCTSN 64

brain-specific angiogenesis inhibitor 2, a group VII adhesion GPCR, member of the class B2 family of seven-transmembrane G protein-coupled receptors; Brain-specific angiogenesis inhibitors (BAI1-3) constitute the group VII of cell-adhesion receptors that have been implicated in vascularization of glioblastomas. They belong to the B2 subfamily of class B GPCRs, are predominantly expressed in the brain, and are only present in vertebrates. Three BAIs, like all adhesion receptors, are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. For example, BAI1 N-terminus contain an integrin-binding RGD (Arg-Gly-Asp) motif in addition to five thrombospondin type 1 repeats (TSRs), which are known to regulate the anti-angiogenic activity of thrombospondin-1, whereas BAI2 and BAI3 have four TSRs, but do not possess RGD motifs. The TSRs are functionally involved in cell attachment, activation of latent TGF-beta, inhibition of angiogenesis and endothelial cell migration. The TSRs of BAI1 mediates direct binding to phosphatidylserine, which enables both recognition and internalization of apoptotic cells by phagocytes. Thus, BAI1 functions as a phosphatidylserine receptor that forms a trimeric complex with ELMO and Dock180, leading to activation of Rac-GTPase which promotes the binding and phagocytosis of apoptotic cells. BAI3 can also interact with the ELMO-Dock180 complex to activate the Rac pathway and can also bind to secreted C1ql proteins of the C1Q complement family via its N-terminal TSRs. BAI3 and its ligands C1QL1 are highly expressed during synaptogenesis and are involved in synapse specificity. Moreover, BAI2 acts as a transcription repressor to regulate vascular endothelial growth factor (VEGF) expression through interaction with GA-binding protein gamma (GABP). The N-terminal extracellular domains of all three BAIs also contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain, which undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif to generate N- and C-terminal fragments (NTF and CTF), a putative hormone-binding domain (HBD), and multiple N-glycosylation sites. The C-terminus of each BAI subtype ends with a conserved Gln-Thr-Glu-Val (QTEV) motif known to interact with PDZ domain-containing proteins, but only BAI1 possesses a proline-rich region, which may be involved in protein-protein interactions.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371  929 AGSPSVPLVIGCAVSCMALLTLLAIYAAFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFL 1008
Cdd:cd15988     1 TGSPSVPLMIGCAVSCMALLILLAIYAAFWRFIRSERSIILLNFCLSILASNILILVGQSQTLSKGVCTMTAAFLHFFFL 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1009 SSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTSSYCWLSLEGGLLYAFVGPAAVIV 1088
Cdd:cd15988    81 SSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTASYCWLSLEGGLLYAFVGPAAVIV 160

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1089 LVNMLIGIIVFNKLMARDGISDKSKKQRAG---------------------------------ASLWSSCVVLPLLALTW 1135
Cdd:cd15988   161 LVNMLIGIIVFNKLMSRDGISDKSKKQRAGseaepcsslllkcskcgvvssaamssatassamASLWSSCVVLPLLALTW 240

                         250       260       270       280       290
                  ....*....|....*....|....*....|....*....|....*....|.
gi 661567371 1136 MSAVLAMTDRRSVLFQALFAVFNSAQGFVITAVHCFLRREVQDVVKCQMGV 1186
Cdd:cd15988   241 MSAVLAMTDRRSILFQVLFAVFNSVQGFVIITVHCFLRREVQDVVKCQMGG 291

brain-specific angiogenesis inhibitor 1, a group VII adhesion GPCR, member of the class B2 family of seven-transmembrane G protein-coupled receptors; Brain-specific angiogenesis inhibitors (BAI1-3) constitute the group VII of cell-adhesion receptors that have been implicated in vascularization of glioblastomas. They belong to the B2 subfamily of class B GPCRs, are predominantly expressed in the brain, and are only present in vertebrates. Three BAIs, like all adhesion receptors, are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. For example, BAI1 N-terminus contain an integrin-binding RGD (Arg-Gly-Asp) motif in addition to five thrombospondin type 1 repeats (TSRs), which are known to regulate the anti-angiogenic activity of thrombospondin-1, whereas BAI2 and BAI3 have four TSRs, but do not possess RGD motifs. The TSRs are functionally involved in cell attachment, activation of latent TGF-beta, inhibition of angiogenesis and endothelial cell migration. The TSRs of BAI1 mediates direct binding to phosphatidylserine, which enables both recognition and internalization of apoptotic cells by phagocytes. Thus, BAI1 functions as a phosphatidylserine receptor that forms a trimeric complex with ELMO and Dock180, leading to activation of Rac-GTPase which promotes the binding and phagocytosis of apoptotic cells. BAI3 can also interact with the ELMO-Dock180 complex to activate the Rac pathway and can also bind to secreted C1ql proteins of the C1Q complement family via its N-terminal TSRs. BAI3 and its ligands C1QL1 are highly expressed during synaptogenesis and are involved in synapse specificity. Moreover, BAI2 acts as a transcription repressor to regulate vascular endothelial growth factor (VEGF) expression through interaction with GA-binding protein gamma (GABP). The N-terminal extracellular domains of all three BAIs also contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain, which undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif to generate N- and C-terminal fragments (NTF and CTF), a putative hormone-binding domain (HBD), and multiple N-glycosylation sites. The C-terminus of each BAI subtype ends with a conserved Gln-Thr-Glu-Val (QTEV) motif known to interact with PDZ domain-containing proteins, but only BAI1 possesses a proline-rich region, which may be involved in protein-protein interactions.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371  926 LELAGSPSVPLVIGCAVSCMALLTLLAIYAAFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHF 1005
Cdd:cd15990     1 MEKALLPSVTLIVGCGVSSLTLLLLIIIYVSVWRYIRSERSVILINFCLSIISSNALILIGQTQTRNKVVCTLVAAFLHF 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1006 FFLSSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTSSYCWLSLEGGLLYAFVGPAA 1085
Cdd:cd15990    81 FFLSSFCWVLTEAWQSYMAVTGRLRNRIIRKRFLCLGWGLPALVVAISVGFTKAKGYGTVNYCWLSLEGGLLYAFVGPAA 160

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1086 VIVLVNMLIGIIVFNKLMARDGISDKSKKQRAGASLWSSCVVLPLLALTWMSAVLAMTDRRSVLFQALFAVFNSAQGFVI 1165
Cdd:cd15990   161 AVVLVNMVIGILVFNKLVSKDGITDKKLKERAGASLWSSCVVLPLLALTWMSAVLAITDRRSALFQILFAVFDSLEGFVI 240

                         250       260
                  ....*....|....*....|....*.
gi 661567371 1166 TAVHCFLRREVQDVVKCQMgVCRADE 1191
Cdd:cd15990   241 VMVHCILRREVQDAVKCRV-VDRQEE 265

Adhesion GPCR B N-terminal region; This region is found at the N-terminus of various adhesion G-protein coupled receptor B proteins. This region contains 10 cysteine residues that probably form disulphide bonds.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371    38 SACSALASGVLYGAFSLQDLFPTIASGCSWTLENPDPTKYSLYLRFNRQEQVCAHFAPRLLPLDHYLVNFTclrpspeea 117
Cdd:pfam19188    1 DPCSTLVQGVLYGSFSLRDLFPTNASGCSWTLENPDPTKYTLYLKFTKPTQSCLPFSPRLLQFDHYLENTT--------- 71

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371   118 vaqaESEVGRPEEEEAeaaagLELCSGSGPFTFLHFDKNFVQLCLSAEPSEAPRLLAPAALAFRFVEVLLINNNNSSQFT 197
Cdd:pfam19188   72 ----RTYLGRESFDEV-----VELCDASSPFSFLEFDKNFVQLCLLAEPRGDPESVVPGPSGDFKVEVLVINNENPSQFT 142

                          170       180       190
                   ....*....|....*....|....*....|....*
gi 661567371   198 CGVLCRWSEECGRAA--GRACGFAQPGCSCPGEAG 230
Cdd:pfam19188  143 CGVLCRWLEECLSAStsSRPCGIMQTPCICPGTVP 177

adhesion receptors, subfamily B2 of the class B family of seven-transmembrane G protein-coupled receptors; The B2 subfamily of class B GPCRs consists of cell-adhesion receptors with 33 members in humans and vertebrates. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing a variety of structural motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, linked to a class B seven-transmembrane domain. These include, for example, EGF (epidermal growth factor)-like domains in CD97, Celsr1 (cadherin family member), Celsr2, Celsr3, EMR1 (EGF-module-containing mucin-like hormone receptor-like 1), EMR2, EMR3, and Flamingo; two laminin A G-type repeats and nine cadherin domains in Flamingo and its human orthologs Celsr1, Celsr2 and Celsr3; olfactomedin-like domains in the latrotoxin receptors; and five or four thrombospondin type 1 repeats in BAI1 (brain-specific angiogenesis inhibitor 1), BAI2 and BAI3. Furthermore, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR- autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371  938 IGCAVSCMALLTLLAIYAAFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFLSSFCWVLTE 1017
Cdd:cd15040    10 IGCGLSLLGLLLTIITYILFRKLRKRKPTKILLNLCLALLLANLLFLFGINSTDNPVLCTAVAALLHYFLLASFMWMLVE 89

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1018 AWQSYLAVIGRMRT--RLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTSSYCWLSLEGGLLYAFVGPAAVIVLVNMLIG 1095
Cdd:cd15040    90 ALLLYLRLVKVFGTypRHFILKYALIGWGLPLIIVIITLAVDPDSYGNSSGYCWLSNGNGLYYAFLGPVLLIILVNLVIF 169

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1096 IIVFNKLMARDGISDKSKKQRAGASLWSSCVVLPLLALTWMSAVLAMTDRRSVlFQALFAVFNSAQGFVITAVHCFLRRE 1175
Cdd:cd15040   170 VLVLRKLLRLSAKRNKKKRKKTKAQLRAAVSLFFLLGLTWIFGILAIFGARVV-FQYLFAIFNSLQGFFIFIFHCLRNKE 248

                  ...
gi 661567371 1176 VQD 1178
Cdd:cd15040   249 VRK 251

class B family of seven-transmembrane G protein-coupled receptors; The class B of seven-transmembrane GPCRs is classified into three major subfamilies: subfamily B1 (secretin-like receptor family), B2 (adhesion family), and B3 (Methuselah-like family). The class B receptors have been identified in all the vertebrates, from fishes to mammals, as well as invertebrates including Caenorhabditis elegans and Drosophila melanogaster, but are not present in plants, fungi or prokaryotes. The B1 subfamily comprises receptors for polypeptide hormones of 27-141 amino-acid residues such as secretin, glucagon, glucagon-like peptide (GLP), calcitonin gene-related peptide, parathyroid hormone (PTH), and corticotropin-releasing factor. These receptors contain the large N-terminal extracellular domain (ECD), which plays a critical role in hormone recognition by binding to the C-terminal portion of the peptide. On the other hand, the N-terminal segment of the hormone induces receptor activation by interacting with the receptor transmembrane domains and connecting extracellular loops, triggering intracellular signaling pathways. All members of the subfamily B1 receptors preferentially couple to G proteins of G(s) family, which positively stimulate adenylate cyclase, leading to increased intracellular cAMP formation and calcium influx. The subfamily B2 consists of cell-adhesion receptors with 33 members in humans and vertebrates. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing a variety of structural motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, linked to a class B seven-transmembrane domain. These include, for example, EGF (epidermal growth factor)-like domains in CD97, Celsr1 (cadherin family member), Celsr2, Celsr3, EMR1 (EGF-module-containing mucin-like hormone receptor-like 1), EMR2, EMR3, and Flamingo; two laminin A G-type repeats and nine cadherin domains in Flamingo and its human orthologs Celsr1, Celsr2 and Celsr3; olfactomedin-like domains in the latrotoxin receptors; and five or four thrombospondin type 1 repeats in BAI1 (brain-specific angiogenesis inhibitor 1), BAI2 and BAI3. Almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR- autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. Furthermore, the subfamily B3 includes Methuselah (Mth) protein, which was originally identified in Drosophila as a GPCR affecting stress resistance and aging, and its closely related proteins.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371  937 VIGCAVSCMALLTLLAIYAAFWRFIKSeRSIILLNFCLSILASNILILVGQSRVLSKG--VCTMTAAFLHFFFLSSFCWV 1014
Cdd:cd13952     9 YIGCSLSLVGLLLTIITYLLFPKLRNL-RGKILINLCLSLLLAQLLFLIGQLLTSSDRpvLCKALAILLHYFLLASFFWM 87

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1015 LTEAWQSYLAVIGRMRTRLvRKRFL---CLGWGLPALVVAVSVGFTRT----KGYGTSSYCWLSLEGGLLYAFVGPAAVI 1087
Cdd:cd13952    88 LVEAFDLYRTFVKVFGSSE-RRRFLkysLYGWGLPLLIVIITAIVDFSlygpSPGYGGEYCWLSNGNALLWAFYGPVLLI 166

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1088 VLVNMLIGIIVFNKLMARDGISDK-SKKQRAGASLWSSCVVLPLLALTWMSAVLAMTDRRSVLFQALFAVFNSAQGFVIT 1166
Cdd:cd13952   167 LLVNLVFFILTVRILLRKLRETPKqSERKSDRKQLRAYLKLFPLMGLTWIFGILAPFVGGSLVFWYLFDILNSLQGFFIF 246

                         250
                  ....*....|.
gi 661567371 1167 AVHCFLRREVQ 1177
Cdd:cd13952   247 LIFCLKNKEVR 257

GPCR-Autoproteolysis INducing (GAIN) domain; The GAIN a domain of alpha-helices and beta-strands that is found in cell-adhesion GPCRs and precedes the GPS motif where the autoproteolysis occurs, family, pfam01825. The full GAIN domain, comprises the GPS and the GAIN, in cell-adhesion GPCRs, and is the functional unit for autoproteolysis. The GPS motif at the end of the GAIN domain is an ancient domain that exists in primitive ancestor organizms, and the full GAIN + GPS is conserved in all cell-adhesion GPCRs and all PKD1-related proteins.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371   614 GMSQVVRSLQELLARRTYYSGDLLFSVDILRNVTDTFKRATYVPSADDVQRFFQVVSFMVDAENKEKWDDAQQVSPGSVH 693
Cdd:pfam16489    1 GAKELARELRNATRHGPLYGGDVLTAVELLSQLFDLLATQDATLSNAFLENFVQTVSNLLDPENRESWEDLQQTERGTAA 80

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371   694 --LLRVVEDFIHLVGDALKAFQSSLIVTDNLVISIQRE--PVSAVSSDITFPMRGRRGmkdwvrHSEDRLFLPKEVLSLS 769
Cdd:pfam16489   81 tkLLRTLEEYALLLAQNMKYLTPFTIVTPNIVLSVDRLdtHNFKGARFPRFPMKGERP------KDEDSVKLPPKAFKPP 154

cadherin EGF LAG seven-pass G-type receptors, group IV adhesion GPCRs, member of the class B2 family of seven-transmembrane G protein-coupled receptors; The group IV adhesion GPCRs include the cadherin EGF LAG seven-pass G-type receptors (CELSRs) and their Drosophila homolog Flamingo (also known as Starry night). These receptors are also classified as that belongs to the EGF-TM7 group of subfamily B2 adhesion GPCRs, because they contain EGF-like domains. Functionally, the group IV receptors act as key regulators of many physiological processes such as endocrine cell differentiation, neuronal migration, dendrite growth, axon, guidance, lymphatic vessel and valve formation, and planar cell polarity (PCP) during embryonic development. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. In the case of CELSR/Flamingo/Starry night, their extracellular domains comprise nine cadherin repeats linked to a series of epidermal growth factor (EGF)-like and laminin globular (G)-like domains. The cadherin repeats contain sequence motifs that mediate calcium-dependent cell-cell adhesion by homophilic interactions. Moreover, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR- autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. Three mammalian orthologs of Flamingo, Celsr1-3, are widely expressed in the nervous system from embryonic development until the adult stage. Each Celsr exhibits different expression patterns in the developing brain, suggesting that they serve distinct functions. Mutations of CELSR1 cause neural tube defects in the nervous system, while mutations of CELSR2 are associated with coronary heart disease. Moreover, CELSR1 and several other PCP signaling molecules, such as dishevelled, prickle, frizzled, have been shown to be upregulated in B lymphocytes of chronic lymphocytic leukemia patients. Celsr3 is expressed in both the developing and adult mouse brain. It has been functionally implicated in proper neuron migration and axon guidance in the CNS.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371  938 IGCAVSCMALLTLLAIYAAFwRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFLSSFCWVLTE 1017
Cdd:cd15441    10 IGIGISLVLLVIAFLVLSCL-RGLQSNSNSIHKNLVACLLLAELLFLLGINQTENLFPCKLIAILLHYFYLSAFSWLLVE 88

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1018 AWQSYlavigRMRT--RLVRK---RF-LCLGWGLPALVVAVSVGFtRTKGYGTSSYCWLSLEGGLLYAFVGPAAVIVLVN 1091
Cdd:cd15441    89 SLHLY-----RMLTepRDINHghmRFyYLLGYGIPAIIVGLSVGL-RPDGYGNPDFCWLSVNETLIWSFAGPIAFVIVIT 162

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1092 MLIGIIVFNKLMARDGISDKSKKQRAGasLWSSCVVLPLLALTWMSAVLAMTDrRSVLFQALFAVFNSAQGFVITAVHCF 1171
Cdd:cd15441   163 LIIFILALRASCTLKRHVLEKASVRTD--LRSSFLLLPLLGATWVFGLLAVNE-DSELLHYLFAGLNFLQGLFIFLFYCI 239

                  ....*
gi 661567371 1172 LRREV 1176
Cdd:cd15441   240 FNKKV 244

epidermal growth factor-like module-containing mucin-like hormone receptors, member of the class B2 family of seven-transmembrane G protein-coupled receptors; group II adhesion GPCRs, including the epidermal growth factor (EGF)-module-containing, mucin-like hormone receptor (EMR1-4) and the leukocyte cell-surface antigen CD97, are primarily expressed in cells of the immune system. All EGF-TM7 receptors, which belong to the B2 subfamily of adhesion GPCRs, are members of group II, except for ETL (EGF-TM7-latrophilin related protein), which is classified into group I. Members of the EGF-TM7 receptors are characterized by the presence of varying number of N-terminal EGF-like domains, which play critical roles in ligand recognition and cell adhesion, linked by a stalk region to a class B seven-transmembrane domain. In the case of EMR2, alternative splicing results in four isoforms possessing either two (EGF1,2), three (EGF1,2,5), four (EGF1,2,3,5) or five (EGF1,2,3,4,5) EGF-like domains. Moreover, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. EMR2 shares strong sequence homology with CD97, differing by only six amino acids. CD97 is widely expressed on lymphocytes, monocytes, macrophages, dendritic cells, granulocytes and smooth muscle cells as well as in a variety of human tumors including colorectal, gastric, esophageal pancreatic, and thyroid carcinoma. However, unlike CD97, EMR2 is not found in those of CD97-positive tumor cells and is not expressed on lymphocytes but instead on monocytes, macrophages and granulocytes. CD97 has three known ligands: CD55, decay-accelerating factor for regulation of complement system; chondroitin sulfate, a glycosaminoglycan found in the extracellular matrix; and the integrin alpha5beta1, which play a role in angiogenesis. Although EMR2 does not effectively interact with CD55, the fourth EGF-like domain of this receptor binds to chondroitin sulfate to mediate cell attachment.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371  938 IGCAVS--CM--ALLTLLaiyaaFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFLSSFCW 1013
Cdd:cd15439    10 VGLIISllCLflAILTFL-----LCRSIRNTSTSLHLQLSLCLFLADLLFLVGIDRTDNKVLCSIIAGFLHYLFLACFAW 84

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1014 VLTEAWQSYLAV-----IGRMRTRLVRKRFLCL-GWGLPALVVAVSVGfTRTKGYGTSSYCWLSLEGGLLYAFVGPAAVI 1087
Cdd:cd15439    85 MFLEAVHLFLTVrnlkvVNYFSSHRFKKRFMYPvGYGLPAVIVAISAA-VNPQGYGTPKHCWLSMEKGFIWSFLGPVCVI 163

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1088 VLVNMLIGIIVF----NKLMARDgiSDKSKKQRAGASLWSSCVVLPLLALTWMSAVLAMTDRRSVLfQALFAVFNSAQGF 1163
Cdd:cd15439   164 IVINLVLFCLTLwilrEKLSSLN--AEVSTLKNTRLLTFKAIAQLFILGCTWILGLFQVGPVATVM-AYLFTITNSLQGV 240

                         250
                  ....*....|....*
gi 661567371 1164 VITAVHCFLRREVQD 1178
Cdd:cd15439   241 FIFLVHCLLNRQVRE 255

orphan GPR116 and related proteins, group IV adhesion GPCRs, member of the class B2 family of seven-transmembrane G protein-coupled receptors; group VI adhesion GPCRs consist of orphan receptors GPR110, GPR111, GPR113, GPR115, GPR116, and closely related proteins. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in ligand recognition as well as cell-cell adhesion and cell-matrix interactions, linked by a stalk region to a class B seven-transmembrane domain. GPR110 possesses a SEA box in the N-terminal has been identified as an oncogene over-expressed in lung and prostate cancer. GPR113 contains a hormone binding domain and one EGF (epidermal grown factor) domain. GPR112 has extremely long N-terminus (about 2,400 amino acids) containing a number of Ser/Thr-rich glycosylation sites and a pentraxin (PTX) domain. GPR116 has two C2-set immunoglobulin-like repeats, which is found in the members of the immunoglobulin superfamily of cell surface proteins, and a SEA (sea urchin sperm protein, enterokinase, and a grin)-box, which is present in the extracellular domain of the transmembrane mucin (MUC) family and known to enhance O-glycosylation. In addition, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. However, several adhesion GPCRs, including GPR 111, GPR115, and CELSR1, are predicted to be non-cleavable at the GAIN domain because of the lack of a consensus catalytic triad sequence (His-Leu-Ser/Thr) within their GPS.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371  938 IGCAVSCMALLTLLAIYAAFWRFIKSE-----RSIILLNFCLSILASNILILVG---QSRVLSKGVCTMTAAFLHFFFLS 1009
Cdd:cd15932    10 VGLGISILSLVLCLIIEALVWKSVTKNktsymRHVCLVNIALSLLIADIWFIIGaaiSTPPNPSPACTAATFFIHFFYLA 89

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1010 SFCWVLTeawqsyLAVIGRMRTRLV-----RKRFL----CLGWGLPALVVAVSVGFTR-TKGYGTSSYCWLSL-EGGLLY 1078
Cdd:cd15932    90 LFFWMLT------LGLLLFYRLVLVfhdmsKSTMMaiafSLGYGCPLIIAIITVAATApQGGYTRKGVCWLNWdKTKALL 163

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 661567371 1079 AFVGPAAVIVLVNMLIGIIVFNKLMaRDGISDKSKKQRAGASLW-SSCVVL--PLLALTWMSAVLAMTDRRSVLFQALFA 1155
Cdd:cd15932   164 AFVIPALAIVVVNFIILIVVIFKLL-RPSVGERPSKDEKNALVQiGKSVAIltPLLGLTWGFGLGTMIDPKSLAFHIIFA 242