C1QB (complement C1q B chain)

Gene

• Entrez ID: 713
• Gene name: Complement C1q B chain
• Gene symbol: C1QB
• Synonyms: -
• Chromosome: 1
• Chromosome location: 1p36.12
• Summary: This gene encodes the B-chain polypeptide of serum complement subcomponent C1q, which associates with C1r and C1s to yield the first component of the serum complement system. 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. C1q deficiency is associated with lupus erythematosus and glomerulonephritis. [provided by RefSeq, Dec 2016]

SNPs

SNP ID	Visualize variation	Clinical significance	Consequence
rs34813378	G>A	Pathogenic	Coding sequence variant, missense variant
rs1064797108	C>-	Likely-pathogenic	Coding sequence variant, frameshift variant
rs1361922961	G>C,T	Pathogenic	Splice donor variant

miRNA

miRTarBase ID	miRNA	Experiments	Reference
MIRT030305	hsa-miR-26b-5p	Microarray	19088304

Gene ontology (GO)

GO ID	Ontology	Definition	Evidence	Reference
GO:0005515	Function	Protein binding	IPI	7240, 12960167, 21054788, 28018340, 32296183
GO:0005576	Component	Extracellular region	TAS
GO:0005581	Component	Collagen trimer	IEA
GO:0005602	Component	Complement component C1 complex	TAS	1706597
GO:0006956	Process	Complement activation	TAS
GO:0006958	Process	Complement activation, classical pathway	TAS
GO:0030449	Process	Regulation of complement activation	TAS
GO:0045087	Process	Innate immune response	IEA
GO:0045202	Component	Synapse	ISS
GO:0062023	Component	Collagen-containing extracellular matrix	HDA	25037231, 28675934
GO:0072562	Component	Blood microparticle	HDA	22516433
GO:0098794	Component	Postsynapse	ISS
GO:0098883	Process	Synapse pruning	ISS

Other IDs

• MIM: 120570
• HGNC: 1242
• e!Ensembl: ENSG00000173369

Protein

• UniProt ID: P02746
• Protein name: Complement C1q subcomponent subunit B
• 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	30 → 86	Collagen triple helix repeat (20 copies)	Repeat
  PF01391	Collagen	60 → 120	Collagen triple helix repeat (20 copies)	Repeat
  PF00386	C1q	123 → 247	C1q domain	Domain

• Sequence:

  MMMKIPWGSIPVLMLLLLLGLIDISQAQLSCTGPPAIPGIPGIPGTPGPDGQPGTPGIKG
  EKGLPGLAGDHGEFGEKGDPGIPGNPGKVGPKGPMGPKGGPGAPGAPGPKGESGDYKATQ
  KIAFSATRTINVPLRRDQTIRFDHVITNMNNNYEPRSGKFTCKVPGLYYFTYHASSRGNL
  CVNLMRGRERAQKVVTFCDYAYNTFQVTTGGMVLKLEQGENVFLQATDKNSLLGMEGANS
  IFSGFLLFPDMEA

• Sequence length: 253