C1QA (complement C1q A chain)

Gene

• Entrez ID: 712
• Gene name: Complement C1q A chain
• Gene symbol: C1QA
• Synonyms: -
• Chromosome: 1
• Chromosome location: 1p36.12
• Summary: 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. [provided by RefSeq, Nov 2016]

SNPs

SNP ID	Visualize variation	Clinical significance	Consequence
rs34139950	G>A	Pathogenic	Stop gained, coding sequence variant
rs121909581	C>T	Pathogenic	Stop gained, coding sequence variant
rs1570073403	G>A	Likely-pathogenic, uncertain-significance	Coding sequence variant, missense variant

miRNA

miRTarBase ID	miRNA	Experiments	Reference
MIRT017487	hsa-miR-335-5p	Microarray	18185580

Gene ontology (GO)

GO ID	Ontology	Definition	Evidence	Reference
GO:0001540	Function	Amyloid-beta binding	TAS	15269255
GO:0001774	Process	Microglial cell activation	ISS
GO:0005515	Function	Protein binding	IPI	7240, 12960167, 21054788, 21988832, 28018340, 28325905, 32296183
GO:0005576	Component	Extracellular region	TAS
GO:0005581	Component	Collagen trimer	IEA
GO:0005602	Component	Complement component C1 complex	TAS	9461517
GO:0006956	Process	Complement activation	TAS
GO:0006958	Process	Complement activation, classical pathway	TAS
GO:0007267	Process	Cell-cell signaling	TAS	9461517
GO:0007568	Process	Aging	ISS
GO:0010039	Process	Response to iron ion	IEA
GO:0016032	Process	Viral process	IEA
GO:0016322	Process	Neuron remodeling	ISS
GO:0030449	Process	Regulation of complement activation	TAS
GO:0045087	Process	Innate immune response	IEA
GO:0045202	Component	Synapse	ISS
GO:0048143	Process	Astrocyte activation	ISS
GO:0050808	Process	Synapse organization	ISS
GO:0062023	Component	Collagen-containing extracellular matrix	HDA	28675934
GO:0098794	Component	Postsynapse	ISS
GO:0098883	Process	Synapse pruning	ISS
GO:0150062	Process	Complement-mediated synapse pruning	ISS
GO:0150064	Process	Vertebrate eye-specific patterning	ISS
GO:1901216	Process	Positive regulation of neuron death	ISS

Other IDs

• MIM: 120550
• HGNC: 1241
• e!Ensembl: ENSG00000173372

Protein

• UniProt ID: P02745
• Protein name: Complement C1q subcomponent subunit A
• 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.
• PDB: 1PK6, 2JG8, 2JG9, 2WNU, 2WNV, 5HKJ, 5HZF, 6FCZ, 6Z6V
• Family and domains:

  Pfam

  Accession	ID	Position in sequence	Description	Type
  PF01391	Collagen	59 → 112	Collagen triple helix repeat (20 copies)	Repeat
  PF00386	C1q	116 → 241	C1q domain	Domain

• Sequence:

  MEGPRGWLVLCVLAISLASMVTEDLCRAPDGKKGEAGRPGRRGRPGLKGEQGEPGAPGIR
  TGIQGLKGDQGEPGPSGNPGKVGYPGPSGPLGARGIPGIKGTKGSPGNIKDQPRPAFSAI
  RRNPPMGGNVVIFDTVITNQEEPYQNHSGRFVCTVPGYYYFTFQVLSQWEICLSIVSSSR
  GQVRRSLGFCDTTNKGLFQVVSGGMVLQLQQGDQVWVEKDPKKGHIYQGSEADSVFSGFL
  IFPSA

• Sequence length: 245