Complement component 4B

Complement component 4B (Chido blood group)
Available structures PDB Ortholog search: PDBe, RCSB List of PDB id codes 1HZF, 4FXG, 4FXK, 4XAM
Identifiers
Symbols	C4B ; C4B1; C4B12; C4B2; C4B3; C4B5; C4BD; C4B_2; C4F; CH; CO4; CPAMD3
External IDs	OMIM: 120820 HomoloGene: 36030 GeneCards: C4B Gene
Gene ontology Molecular function • complement binding • endopeptidase inhibitor activity • carbohydrate binding Cellular component • extracellular region • extracellular space • plasma membrane • other organism cell • extracellular exosome • blood microparticle Biological process • inflammatory response • complement activation • complement activation, classical pathway • opsonization • negative regulation of endopeptidase activity • regulation of complement activation • detection of molecule of bacterial origin • innate immune response • positive regulation of apoptotic cell clearance Sources: Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	721	12268
Ensembl	ENSG00000224639	ENSMUSG00000073418
UniProt	P0C0L4	P01029
RefSeq (mRNA)	NM_001002029	NM_009780
RefSeq (protein)	NP_001002029	NP_033910
Location (UCSC)	Chr 6: 32.01 – 32.04 Mb	Chr 17: 34.73 – 34.74 Mb
PubMed search

Complement component 4B (Chido blood group) is a protein that in humans is encoded by the C4B gene.^[1]

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].^[1]

References

1. "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.