 Sema domain, immunoglobulin domain (Ig), short basic domain | |||||||||
| Identifiers | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Symbol | Sema | ||||||||
| Pfam | PF01403 | ||||||||
| InterPro | IPR001627 | ||||||||
| PROSITE | PDOC51004 | ||||||||
| SCOP2 | 1olz / SCOPe / SUPFAM | ||||||||
| Membranome | 71 | ||||||||
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The Sema domain is a structural domain of semaphorins, which are a large family of secreted and transmembrane proteins, some of which function as repellent signals during axon guidance. Sema domains also occur in the hepatocyte growth factor receptor (Uniprot: P08581), Plexin-A3 [1] (Uniprot: P51805) and in viral proteins.
CD100 (also called SEMA4D) is associated with PTPase and serine kinase activity. CD100 increases PMA, CD3 and CD2 induced T cell proliferation, increases CD45 induced T cell adhesion, induces B cell homotypic adhesion and down-regulates B cell expression of CD23.
The Sema domain is characterised by a conserved set of cysteine residues, which form four disulfide bonds to stabilise the structure. The Sema domain fold is a variation of the beta propeller topology, with seven blades radially arranged around a central axis. Each blade contains a four- stranded (strands A to D) antiparallel beta sheet. The inner strand of each blade (A) lines the channel at the centre of the propeller, with strands B and C of the same repeat radiating outward, and strand D of the next repeat forming the outer edge of the blade. The large size of the Sema domain is not due to a single inserted domain but results from the presence of additional secondary structure elements inserted in most of the blades. The Sema domain uses a 'loop and hook' system to close the circle between the first and the last blades. The blades are constructed sequentially with an N-terminal beta- strand closing the circle by providing the outermost strand (D) of the seventh (C-terminal) blade. The beta-propeller is further stabilized by an extension of the N-terminus, providing an additional, fifth beta-strand on the outer edge of blade 6.[2][3][4]
- ^ Winberg ML, Noordermeer JN, Tamagnone L, Comoglio PM, Spriggs MK, Tessier-Lavigne M, Goodman CS (December 1998). "Plexin A is a neuronal semaphorin receptor that controls axon guidance". Cell. 95 (7): 903–16. doi:10.1016/S0092-8674(00)81715-8. PMID 9875845. S2CID 14703056.
- ^ Antipenko A, Himanen JP, van Leyen K, Nardi-Dei V, Lesniak J, Barton WA, Rajashankar KR, Lu M, Hoemme C, Püschel AW, Nikolov DB (August 2003). "Structure of the semaphorin-3A receptor binding module". Neuron. 39 (4): 589–98. doi:10.1016/S0896-6273(03)00502-6. PMID 12925274. S2CID 9782923.
- ^ Love CA, Harlos K, Mavaddat N, Davis SJ, Stuart DI, Jones EY, Esnouf RM (October 2003). "The ligand-binding face of the semaphorins revealed by the high-resolution crystal structure of SEMA4D". Nature Structural Biology. 10 (10): 843–8. doi:10.1038/nsb977. PMID 12958590. S2CID 24468463.
- ^ Stamos J, Lazarus RA, Yao X, Kirchhofer D, Wiesmann C (June 2004). "Crystal structure of the HGF beta-chain in complex with the Sema domain of the Met receptor". The EMBO Journal. 23 (12): 2325–35. doi:10.1038/sj.emboj.7600243. PMC 423285. PMID 15167892.