[CITATION][C] The SRCR superfamily: a family reminiscent of the Ig superfamily

D Resnick, A Pearson, M Krieger - Trends in biochemical sciences, 1994 - Elsevier
D Resnick, A Pearson, M Krieger
Trends in biochemical sciences, 1994Elsevier
Many proteins are molecular mosaics composed of a wide variety of conserved sequence
motifs which comprise structurally distinct domains. in many cases, these motifs are
characterized by short, disulfide-stabilized domains present in the extracellular portions of
membrane proteins and in secreted proteins, 2. Examples include the immunoglobulin
repeat 3, 4, kringle domains, epidermal growth factor (EGF) 4ike repeats, complement
Cg/LDL-receptor domains, Ly-6 repeats 5, 6 and the P-domain 7. These domains are well …
Many proteins are molecular mosaics composed of a wide variety of conserved sequence motifs which comprise structurally distinct domains. in many cases, these motifs are characterized by short, disulfide-stabilized domains present in the extracellular portions of membrane proteins and in secreted proteins, 2. Examples include the immunoglobulin repeat 3, 4, kringle domains, epidermal growth factor (EGF) 4ike repeats, complement Cg/LDL-receptor domains, Ly-6 repeats 5, 6 and the P-domain 7. These domains are well suited for a variety of biochemical tasks, including ligand binding, and are readily combined with themselves or with other types of domains for the construction of complex mosaic proteins. Proteins containing as few as one and as many as 36 copies of any one single type of domain have been reported 8, 9. One ancient and highly conserved family of cysteine-rich protein domains was recognized during the analysis of the structure of the type I macrophage scavenger receptor 1, n. This class of domain, designated the SRCR (scavenger receptor cysteine-rich) domain, was initially defined by the presence of one to four copies per polypeptide chain of an approximately 101-residue motif inthe type I scavenger receptor, the sDeract receptor, CDS/Lyl and complement factor l (CFI)(a total of 13 sequences, including nine independent sequences and four sequences of homologs from different species). The recent cloning of genes encoding 24 additional, independent SRCR domains, and ten additional homologs, has allowed us to revise our initial description of the consensus SRCR domain and to define two distinct subgroups. The recently available sequences, which were identified using the programs BLASTN and TBLASTN 12, are those of CD6 (Ref. 13), the cyclophilin-C-binding protein 4 and its homolog the MAC2-binding protein s (CyCAP/MAC2-bp), the WCl antigen= 6, M130 (Ref. 17), a new CR homolog (EMBL accession No. S15468), and two new homologs each of CD5/Lyl (Refs 18, 19) and the scawenger receptor 2, 21. Thus, the superfami~ y of SRCR-domaincontaining proteins, includes eight different members derived from five mammalian (human, bovine, murine, rat and rabbit), one amphibian (Xenopus laevis) and one invertebrate (sea urchin)
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