InterPro domain: IPR001190

The scavenger receptor cysteine-rich (SRCR) domain is an ancient and highlyconserved domain of about 110 residues which is found in diverse secreted andcell-surface proteins, like the type I scavenger receptor, the speractreceptor, CD5/Ly-1, CD6, or complement factor I [ 1 ]. Tandem repeats of SRCRdomains are common in the membrane bound proteins. Most SRCR domains have sixto eight cysteines that participate in intradomain disulfide bonds. SRCRdomains have been subdivided into two groups, A and B, primarily on thedifferences in the spacing pattern between the cysteine residues [ 2 , 3 ].

Although the biochemical functions of SRCR domains have not been establishedwith certainty, they are likely to mediate protein-protein interactions andligand binding [ 4 , 4 ].

Determination of the crystal structure of the SRCR domain of M2BP reveals thatthe M2NP SRCR adopts a compact fold of approximate dimensions 22 x 26 x 30Angstrom, organised around a curved six-stranded beta-sheet cradling an alpha-helix [ 4 ].

1. An ancient, highly conserved family of cysteine-rich protein domains revealed by cloning type I and type II murine macrophage scavenger receptors. Proc. Natl. Acad. Sci. U.S.A. 87, 8810-4
2. The SRCR superfamily: a family reminiscent of the Ig superfamily. Trends Biochem. Sci. 19, 5-8
3. Crystal structure of a scavenger receptor cysteine-rich domain sheds light on an ancient superfamily. Nat. Struct. Biol. 6, 228-32