Complement component 2

C2
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 2I6S, 3ERB,%%s2ODQ
Identifiers
Aliases	C2, ARMD14, CO2, complement component 2, complement C2
External IDs	OMIM: 613927 MGI: 88226 HomoloGene: 45 GeneCards: C2
Gene location (Human) Chr. Chromosome 6 (human)[1] Band 6p21.33 Start 31,897,785 bp[1] End 31,945,672 bp[1]
Gene location (Mouse) Chr. Chromosome 17 (mouse)[2] Band 17 B1|17 18.41 cM Start 34,862,604 bp[2] End 34,898,265 bp[2]
RNA expression pattern More reference expression data
Gene ontology Molecular function • peptidase activity • serine-type peptidase activity • hydrolase activity • metal ion binding • serine-type endopeptidase activity • GO:0001948 protein binding Cellular component • extracellular region • extracellular exosome • extracellular space Biological process • complement activation • positive regulation of apoptotic cell clearance • regulation of complement activation • response to nutrient • proteolysis • complement activation, classical pathway • immune system process • innate immune response Sources:Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	717	12263
Ensembl	ENSG00000206372 ENSG00000235017 ENSG00000235696 ENSG00000226560 ENSG00000204364 ENSG00000166278 ENSG00000231543	ENSMUSG00000024371
UniProt	P06681 Q5JP69	P21180
RefSeq (mRNA)	NM_000063 NM_001145903 NM_001178063 NM_001282457 NM_001282458 NM_001282459	NM_013484
RefSeq (protein)	NP_000054 NP_001139375 NP_001171534 NP_001269386 NP_001269387 NP_001269388 NP_000054.2	NP_038512
Location (UCSC)	Chr 6: 31.9 – 31.95 Mb	Chr 17: 34.86 – 34.9 Mb
PubMed search	[3]	[4]
Wikidata
View/Edit Human View/Edit Mouse

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]

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 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 smallest , enzymatically active, fragment of 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

External links

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