C1QA

This gene encodes the A-chain polypeptide of serum complement subcomponent C1q, which associates with C1r and C1s to yield the first component of the serum complement system. C1q deficiency is associated with lupus erythematosus and glomerulonephritis. C1q is composed of 18 polypeptide chains which include 6 A-chains, 6 B-chains, and 6 C-chains. Each chain contains an N-terminal collagen-like region and a C-terminal C1q globular domain. Alternate splicing results in multiple transcript variants.

C1QA

C1q associates with the proenzymes C1r and C1s to yield C1, the first component of the serum complement system. The collagen-like regions of C1q interact with the Ca2+-dependent C1r2C1s2 proenzyme complex, and efficient activation of C1 takes place on interaction of the globular heads of C1q with the Fc regions of IgG or IgM antibody present in immune complexes.

Aging Source: ARUK-UCL
Astrocyte activation Source: ARUK-UCL
Cell-cell signaling Source: ProtInc
Complement activation Source: Reactome
Complement activation, classical pathway Source: Reactome
Complement-mediated synapse pruning Source: ARUK-UCL
Innate immune response Source: UniProtKB-KW
Microglial cell activation Source: ARUK-UCL
Neuron remodeling Source: ARUK-UCL
Positive regulation of neuron death Source: ARUK-UCL
Regulation of complement activation Source: Reactome
Response to iron ion Source: Ensembl
Synapse organization Source: ARUK-UCL
Synapse pruning Source: ARUK-UCL
Vertebrate eye-specific patterning Source: ARUK-UCL
Viral process Source: UniProtKB-KW

Secreted

Complement component C1q deficiency (C1QD): A disorder caused by impaired activation of the complement classical pathway. It generally leads to severe immune complex disease with features of systemic lupus erythematosus and glomerulonephritis.

O-linked glycans are assumed to be the Glc-Gal disaccharides typically found as secondary modifications of hydroxylated lysines in collagen-like domains.