gC1qdomaincontaining

gC1q domain-containing (gC1qDC) proteins are a family of secreted or extracellular proteins defined by the presence of a globular C1q (gC1q) domain at their C terminus. They belong to the C1q/TNF superfamily and are found across vertebrates, with multiple paralogs in many species. The proteins typically have a variable N-terminal region and, in many members, a stalk-like collagenous or other structural segment that precedes the conserved gC1q domain. The gC1q domain mediates oligomerization and ligand binding, and in some family members the proteins assemble into trimers or higher-order multimers.

Functionally, gC1qDC proteins are involved in immune regulation, inflammation, tissue remodeling, and development. They can bind to extracellular matrix components, receptors, or microbial ligands, thereby influencing cell adhesion, migration, cytokine production, and signaling pathways. Despite extensive sequence similarity, functions are best characterized for a subset of family members; many remain poorly characterized.

Genomic distribution and evolution show that gC1qDC genes are part of flexible gene families that have expanded and diversified in vertebrate lineages, with lineage-specific duplications in some groups.

Clinical and biological relevance: due to broad expression, some members have been studied for roles in immunity, metabolism, reproduction, and development, but direct disease associations are limited and contextual.

See also: globular C1q domain, C1q/TNF superfamily, adiponectin, collectins, complement system.