Complement component 2

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Complement component 2
Protein C2 PDB 2i6q.png
PDB rendering based on 2i6q.
Available structures
PDB Ortholog search: PDBe, RCSB
Symbols C2 ; ARMD14; CO2
External IDs OMIM613927 MGI88226 HomoloGene45 GeneCards: C2 Gene
EC number
RNA expression pattern
PBB GE C2 203052 at tn.png
More reference expression data
Species Human Mouse
Entrez 717 12263
Ensembl ENSG00000166278 ENSMUSG00000024371
UniProt P06681 P21180
RefSeq (mRNA) NM_000063 NM_013484
RefSeq (protein) NP_000054 NP_038512
Location (UCSC) Chr 6:
31.9 – 31.95 Mb
Chr 17:
34.86 – 34.9 Mb
PubMed search [1] [2]

Complement C2 is a protein that in humans is encoded by the C2 gene.[1] The protein encoded by this gene is part of the classical pathway of complement system, acting as a multi-domain serine protease. Deficiency of C2 has been associated with certain autoimmune diseases.[1]


In the classical and lectin pathways of complement activation, formation of the C3-convertase and C5-convertases requires binding of C2 to an activated surface-bound C4b in the presence of Mg2+; the resultant C4bC2 complex is then cleaved by C1s or MASP2 into C2a and C2b. It is thought that cleavage of C2 by C1s, while bound to C4b. results into a conformational rotation of C2a whereas the released C2b fragment may retain most of its original structure. C2a is the larger, enzymatically active fragment which is incorporated into the C3 convertase in this pathway, C4b2. C2b is released into the fluid phase.[2]


  1. ^ a b "Entrez Gene: C2 complement component 2". 
  2. ^ Takeuchi E, Doi T, Shimada T, Muso E, Maruyama N, Yoshida H (Feb 1989). "Retroviral gp70 antigen in spontaneous mesangial glomerulonephritis of ddY mice". Kidney International 35 (2): 638–46. PMC 2651757. 

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