Complement component C1q domain.
SMART accession number:SM00110
Description: Globular domain found in many collagens and eponymously in complement C1q. When part of full length proteins these domains form a 'bouquet' due to the multimerization of heterotrimers. The C1q fold is similar to that of tumour necrosis factor.
Interpro abstract (IPR001073):

This entry represents the C-terminal domain of C1q. C1q is a subunit of the C1 enzyme complex that activates the serum complement system. C1q comprises 6 A, 6 B and 6 C chains. These share the same topology, each possessing a small, globular N-terminal domain, a collagen-like Gly/Pro-rich central region, and a conserved C-terminal region, the C1q domain [(PUBMED:1706597)]. The C1q protein is produced in collagen-producing cells and shows sequence and structural similarity to collagens VIII and X [(PUBMED:2591537), (PUBMED:2019595)]. This domain is also found in multimerin and EMILIN proteins.

Family alignment:
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There are 3123 C1Q domains in 3009 proteins in SMART's nrdb database.

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