Complement C4

Function

Complement C4 (CC4) is part of the complement pathway. CC4 is a mixture of CC4-A and CC4-B. CC4 is part of the complement cascade which results in pathogen cell membrane pore and the eventual lysis of the pathogen cell^[1].

Disease

C4 deficiency causes lupus-like autoimmunity^[2]. Copy number variations of complement C4 are associated with Behcet's disease^[3]. Level of complement C4 is associated with persistence and disease progression of chronic hepatitis C^[4].

Glycosylated human complement C4-A α chain (grey), C4 β (green) and γ chain (pink) (PDB code 5jpn)

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3D structures of complement C43D structures of complement C4

Updated on 16-March-2023

5jpn – hCC4a- human
1hzf – hCC4a residues 970-1336
5jtw – hCC4a residues 757-1744 + hCC4-B residues 20-675
5jpn – hCC4a α chain residues 680-1446 + hCC4 β residues 2—675 +γ residues 1454-1744 chains
5jpm – hCC4a α chain residues 680-1446 + hCC4 β residues 2—675 +γ residues 1454-1744 chains + mannan-binding lectin serine protease
6ysq – hCC4b + nanobody
7b2m, 7b2p, 7b2q – hCC4b + nanobody – Cryo EM

ReferencesReferences

↑ Nesargikar PN, Spiller B, Chavez R. The complement system: history, pathways, cascade and inhibitors. Eur J Microbiol Immunol (Bp). 2012 Jun;2(2):103-11. doi:, 10.1556/EuJMI.2.2012.2.2. Epub 2012 Jun 13. PMID:24672678 doi:http://dx.doi.org/10.1556/EuJMI.2.2012.2.2
↑ Chen Z, Koralov SB, Kelsoe G. Complement C4 inhibits systemic autoimmunity through a mechanism independent of complement receptors CR1 and CR2. J Exp Med. 2000 Nov 6;192(9):1339-52. PMID:11067882
↑ Hou S, Qi J, Liao D, Zhang Q, Fang J, Zhou Y, Liu Y, Bai L, Zhang M, Kijlstra A, Yang P. Copy number variations of complement component C4 are associated with Behcet's disease but not with ankylosing spondylitis associated with acute anterior uveitis. Arthritis Rheum. 2013 Nov;65(11):2963-70. doi: 10.1002/art.38116. PMID:23918728 doi:http://dx.doi.org/10.1002/art.38116
↑ Chowdhury SJ, Karra VK, Bharali R, Kar P. Role of complement component C4 in treatment response and disease progression in chronic hepatitis C patients. J Viral Hepat. 2015 Aug;22(8):671-4. doi: 10.1111/jvh.12383. Epub 2015 Jan 9. PMID:25573496 doi:http://dx.doi.org/10.1111/jvh.12383

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Michal Harel, Joel L. Sussman

[1] Nesargikar PN, Spiller B, Chavez R. The complement system: history, pathways, cascade and inhibitors. Eur J Microbiol Immunol (Bp). 2012 Jun;2(2):103-11. doi:, 10.1556/EuJMI.2.2012.2.2. Epub 2012 Jun 13. PMID:24672678 doi:http://dx.doi.org/10.1556/EuJMI.2.2012.2.2

[2] Chen Z, Koralov SB, Kelsoe G. Complement C4 inhibits systemic autoimmunity through a mechanism independent of complement receptors CR1 and CR2. J Exp Med. 2000 Nov 6;192(9):1339-52. PMID:11067882

[3] Hou S, Qi J, Liao D, Zhang Q, Fang J, Zhou Y, Liu Y, Bai L, Zhang M, Kijlstra A, Yang P. Copy number variations of complement component C4 are associated with Behcet's disease but not with ankylosing spondylitis associated with acute anterior uveitis. Arthritis Rheum. 2013 Nov;65(11):2963-70. doi: 10.1002/art.38116. PMID:23918728 doi:http://dx.doi.org/10.1002/art.38116

[4] Chowdhury SJ, Karra VK, Bharali R, Kar P. Role of complement component C4 in treatment response and disease progression in chronic hepatitis C patients. J Viral Hepat. 2015 Aug;22(8):671-4. doi: 10.1111/jvh.12383. Epub 2015 Jan 9. PMID:25573496 doi:http://dx.doi.org/10.1111/jvh.12383

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