Complement C2 is a protein that in humans is encoded by the C2gene. 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.
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.
Johnson CA, Densen P, Hurford RK, Colten HR, Wetsel RA (May 1992). "Type I human complement C2 deficiency. A 28-base pair gene deletion causes skipping of exon 6 during RNA splicing". The Journal of Biological Chemistry267 (13): 9347–53. PMID1577763.
Lappin DF, Birnie GD, Whaley K (Nov 1990). "Interferon-mediated transcriptional and post-transcriptional modulation of complement gene expression in human monocytes". European Journal of Biochemistry / FEBS194 (1): 177–84. doi:10.1111/j.1432-1033.1990.tb19443.x. PMID1701385.
Horiuchi T, Macon KJ, Kidd VJ, Volanakis JE (Mar 1989). "cDNA cloning and expression of human complement component C2". Journal of Immunology142 (6): 2105–11. PMID2493504.
Cole FS, Whitehead AS, Auerbach HS, Lint T, Zeitz HJ, Kilbridge P, Colten HR (Jul 1985). "The molecular basis for genetic deficiency of the second component of human complement". The New England Journal of Medicine313 (1): 11–6. doi:10.1056/NEJM198507043130103. PMID2582254.
Kam CM, McRae BJ, Harper JW, Niemann MA, Volanakis JE, Powers JC (Mar 1987). "Human complement proteins D, C2, and B. Active site mapping with peptide thioester substrates". The Journal of Biological Chemistry262 (8): 3444–51. PMID3546307.
Wu LC, Morley BJ, Campbell RD (Jan 1987). "Cell-specific expression of the human complement protein factor B gene: evidence for the role of two distinct 5'-flanking elements". Cell48 (2): 331–42. doi:10.1016/0092-8674(87)90436-3. PMID3643061.
Gagnon J (Sep 1984). "Structure and activation of complement components C2 and factor B". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences306 (1129): 301–9. doi:10.1098/rstb.1984.0091. PMID6149575.