C1q domain
IPR001073
Definition
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 PMID:1706597. The C1q protein is produced in collagen-producing cells and shows sequence and structural similarity to collagens VIII and X [[cite:PMID:2591537], [cite:PMID:2019595]]. This domain is also found in multimerin and EMILIN proteins. The C-terminal globular domain of the C1q subcomponents and collagen types VIII and X is important both for the correct folding and alignment of the triple helix and for protein-protein recognition events PMID:1867713. For collagen type X it has been suggested that the domain is important for initiation and maintenance of the correct assembly of the protein PMID:1860888. The globular head is a trimer of C1q domains. Each individual C1q adopts a 10-strand Jelly-roll fold arranged in two antiparallel 5-stranded β-sheets PMID:22892318. There are two well conserved regions within the C1q domain: an aromatic motif is located within the first half of the domain, the other conserved region is located near the C-terminal extremity.
33 human proteins with this domain
Each is a reviewed human protein in the Seroatlas serome and a potential autoantibody target; this domain groups them into one antibody-relevant category. Every entry links to its own record.
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