Printable factfile
Gene Information
Names
HUGO name: C1QA
Alias(es):
- Complement component 1, q subcomponent, alpha polypeptide
- Complement C1q subcomponent, A chain precursor
Localization
Reference sequences
Chromosomal location
Maps
Variations / Mutations
Other gene-based resources
Protein Information
Description
Protein function:
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 Ca(2+)-dependent C1r(2)C1s(2) 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.
Subunit:
C1 is a calcium-dependent trimolecular complex of C1q, r and s in the molar ration of 1:2:2. The C1q subcomponent is composed of nine subunits, six of which are disulfide-linked dimers of the a and b chains, and three of which are disulfide-linked dimers of the c chain.
Post-translational modification:
O-linked glycan consists of glc-gal disaccharide.
Structures (PDB)
Domains
Collagen-like domain: 31-109
C1q domain: 110-245
Other features
Signal peptide: 1-22
Complement C1q subcomponent, a chain: 23-245
Disulfide bond interchain (with c-29 in b chain): 26
Other related resourses:
Expression
Expression pattern for human
| Tissue | Expression (%) | Clones |
|---|---|---|
| skin, melanocyte | 16.46 | 1:520 |
| lung with fibrosis | 11.57 | 2:1479 |
| esophagus | 8.71 | 3:2949 |
| normal head/neck tissue | 6.62 | 1:1292 |
| ovary, pooled | 5.86 | 4:5846 |
| spleen | 4.74 | 4:7229 |
| mixed | 4.40 | 31:60341 |
| human eye anterior segment | 4.33 | 1:1978 |
| germ cell | 4.26 | 10:20077 |
| rpe and choroid | 4.05 | 5:10565 |