Complement component 2

Complement C2 is a protein that in humans is encoded by the C2 gene.[5] The protein encoded by this gene is part of the classical pathway of the complement system, acting as a multi-domain serine protease. Deficiency of C2 has been associated with certain autoimmune diseases.[5]

C2
Available structures
PDBOrtholog search: PDBe RCSB
Identifiers
AliasesC2, ARMD14, CO2, complement component 2, complement C2
External IDsOMIM: 613927 MGI: 88226 HomoloGene: 45 GeneCards: C2
Gene location (Human)
Chr.Chromosome 6 (human)[1]
Band6p21.33Start31,897,785 bp[1]
End31,945,672 bp[1]
RNA expression pattern
More reference expression data
Orthologs
SpeciesHumanMouse
Entrez

717

12263

Ensembl

ENSMUSG00000024371

UniProt

P06681
Q5JP69

P21180

RefSeq (mRNA)

NM_013484

RefSeq (protein)

NP_038512

Location (UCSC)Chr 6: 31.9 – 31.95 MbChr 17: 34.86 – 34.9 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

Function

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 in a conformational rotation of C2b whereas the released C2a fragment may retain most of its original structure.

C2b is the larger, enzymatically active fragment which is incorporated into the C3 convertase in this pathway, C4b2b (NB: some sources now refer to the larger fragment of C2 as C2b, making the C3 convertase C4b2b, whereas older sources refer to the larger fragment of C2 as C2a, making the C3 convertase C4b2a). The smaller fragment, C2a (or C2b, depending on the source) is released into the fluid phase.[6]

References

Further reading

  • Complement+2 at the US National Library of Medicine Medical Subject Headings (MeSH)
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