Complement component 4B

C4B
Available structures PDB Human UniProt search: PDBe RCSB List of PDB id codes 1HZF, 4FXG, 4FXK, 4XAM,%%s4XAM
Identifiers
Aliases	C4B, C4B1, C4B12, C4B2, C4B3, C4B5, C4BD, C4B_2, C4F, CH, CO4, CPAMD3, Complement component 4B, complement component 4B (Chido blood group)
External IDs	HomoloGene: 36030 GeneCards: C4B
Gene ontology Molecular function • endopeptidase inhibitor activity • complement component C1q binding • serine-type endopeptidase activity • complement binding • carbohydrate binding Cellular component • extracellular space • extracellular region • plasma membrane • extracellular exosome • blood microparticle • cell projection • dendrite • cell junction • synapse • axon • neuronal cell body • other organism cell Biological process • complement activation • inflammatory response • positive regulation of apoptotic cell clearance • regulation of complement activation • negative regulation of endopeptidase activity • complement activation, classical pathway • immune system process • innate immune response • proteolysis • detection of molecule of bacterial origin • opsonization Sources:Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	721	n/a
Ensembl	n/a	n/a
UniProt	P0C0L4 P0C0L5	n/a
RefSeq (mRNA)	NM_001002029	n/a
RefSeq (protein)	NP_001002029.3 NP_001239133.1 NP_009224.2 NP_001002029.3 NP_001229752.1	n/a
Location (UCSC)	Chr 6: 32.01 – 32.04 Mb	n/a
PubMed search	[1]	n/a
Wikidata

View/Edit Human

Complement component 4B (Chido blood group) is a protein that in humans is encoded by the C4B gene.^[2]

This gene encodes the basic form of complement factor 4, part of the classical activation pathway. The protein is expressed as a single chain precursor which is proteolytically cleaved into a trimer of alpha, beta, and gamma chains prior to secretion. The trimer provides a surface for interaction between the antigen-antibody complex and other complement components. The alpha chain may be cleaved to release C4 anaphylatoxin, a mediator of local inflammation. Deficiency of this protein is associated with systemic lupus erythematosus. This gene localizes to the major histocompatibility complex (MHC) class III region on chromosome 6. Varying haplotypes of this gene cluster exist, such that individuals may have 1, 2, or 3 copies of this gene. In addition, this gene exists as a long form and a short form due to the presence or absence of a 6.4 kb endogenous HERV-K retrovirus in intron 9. [provided by RefSeq, Jul 2008].^[2]

References

1. "Human PubMed Reference:".
2. "Entrez Gene: Complement component 4B (Chido blood group)". Retrieved 2012-01-27.

Further reading

• Yu CY (1998). "Molecular genetics of the human MHC complement gene cluster". Experimental and Clinical Immunogenetics. 15 (4): 213–30. doi:10.1159/000019075. PMID 10072631.
• Yang Z, Mendoza AR, Welch TR, Zipf WB, Yu CY (Apr 1999). "Modular variations of the human major histocompatibility complex class III genes for serine/threonine kinase RP, complement component C4, steroid 21-hydroxylase CYP21, and tenascin TNX (the RCCX module). A mechanism for gene deletions and disease associations". The Journal of Biological Chemistry. 274 (17): 12147–56. doi:10.1074/jbc.274.17.12147. PMID 10207042.
• Blom AM, Webb J, Villoutreix BO, Dahlbäck B (Jul 1999). "A cluster of positively charged amino acids in the C4BP alpha-chain is crucial for C4b binding and factor I cofactor function". The Journal of Biological Chemistry. 274 (27): 19237–45. doi:10.1074/jbc.274.27.19237. PMID 10383431.
• Tas SW, Klickstein LB, Barbashov SF, Nicholson-Weller A (Nov 1999). "C1q and C4b bind simultaneously to CR1 and additively support erythrocyte adhesion". Journal of Immunology. 163 (9): 5056–63. PMID 10528211.
• Aoki H, Takizawa F, Tsuji S, Nagasawa S (Jul 2000). "Elongation factor-1alpha as a homologous complement activator of Jurkat cells". International Journal of Molecular Medicine. 6 (1): 87–92. doi:10.3892/ijmm.6.1.87. PMID 10851272.
• Teisberg P, Akesson I, Olaisen B, Gedde-Dahl T, Thorsby E (Nov 1976). "Genetic polymorphism of C4 in man and localisation of a structural C4 locus to the HLA gene complex of chromosome 6". Nature. 264 (5583): 253–4. doi:10.1038/264253a0. PMID 1088823.
• Pan Q, Ebanks RO, Isenman DE (Sep 2000). "Two clusters of acidic amino acids near the NH2 terminus of complement component C4 alpha'-chain are important for C2 binding". Journal of Immunology. 165 (5): 2518–27. doi:10.4049/jimmunol.165.5.2518. PMID 10946278.
• Kramer J, Harcos P, Prohászka Z, Horváth L, Karádi I, Singh M, Császár A, Romics L, Füst G (Nov 2000). "Frequencies of certain complement protein alleles and serum levels of anti-heat-shock protein antibodies in cerebrovascular diseases". Stroke; A Journal of Cerebral Circulation. 31 (11): 2648–52. doi:10.1161/01.STR.31.11.2648. PMID 11062289.
• Dragon-Durey MA, Rougier N, Clauvel JP, Caillat-Zucman S, Remy P, Guillevin L, Liote F, Blouin J, Ariey F, Lambert BU, Kazatchkine MD, Weiss L (Jan 2001). "Lack of evidence of a specific role for C4A gene deficiency in determining disease susceptibility among C4-deficient patients with systemic lupus erythematosus (SLE)". Clinical and Experimental Immunology. 123 (1): 133–9. doi:10.1046/j.1365-2249.2001.01438.x. PMC 1905972. PMID 11168010.
• Laich A, Sim RB (Jan 2001). "Complement C4bC2 complex formation: an investigation by surface plasmon resonance". Biochimica et Biophysica Acta. 1544 (1-2): 96–112. doi:10.1016/S0167-4838(00)00208-9. PMID 11341920.