C4A

Complement component 4A (Rodgers blood group)
PDB rendering based on 1hzf.
Available structures PDB 1hzf
Identifiers
Symbols	C4A; C4; C4A2; C4A3; C4A4; C4A6; C4S; CO4; CPAMD2; MGC164979; RG
External IDs	OMIM: 120810 MGI: 88228 HomoloGene: 36030 GeneCards: C4A Gene
Gene Ontology Molecular function • endopeptidase inhibitor activity Cellular component • extracellular region • extracellular region • extracellular space Biological process • inflammatory response • complement activation • complement activation, classical pathway • innate immune response Sources: Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	720	12268
Ensembl	ENSG00000244731	n/a
UniProt	P0C0L4	n/a
RefSeq (mRNA)	NM_007293	NM_009780.2
RefSeq (protein)	NP_009224	NP_033910.2
Location (UCSC)	Chr 6: 31.95 – 31.97 Mb	n/a
PubMed search	[1]	[2]

Complement C4-A is a protein that in humans is encoded by the C4A gene.^[1]

This gene encodes the acidic 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 and type I diabetes mellitus^{[2][3][4][5][6][7]}. 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.^[1]

See also

• Complement component 4

References

1. ^ ^{a b} "Entrez Gene: C4A complement component 4A (Rodgers blood group)". http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=720. 
2. ^ Dawkins RL, Uko G, Christiansen FT, Kay PH (1983). "Low C4 concentrations in insulin dependent diabetes mellitus.". Br Med J (Clin Res Ed) 287 (6395): 839. doi:10.1136/bmj.287.6395.839-b. PMC 1549128. PMID 6412852. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1549128. 
3. ^ Vergani D, Johnston C, B-Abdullah N, Barnett AH (1983). "Low serum C4 concentrations: an inherited predisposition to insulin dependent diabetes?". Br Med J (Clin Res Ed) 286 (6369): 926–8. doi:10.1136/bmj.286.6369.926. PMC 1547358. PMID 6403137. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1547358. 
4. ^ Mijovic CH, Fletcher JA, Bradwell AR, Barnett AH (1987). "Low C4 levels in type 1 (insulin-dependent) diabetes". Diabetologia 30 (10): 824. PMID 3428499. 
5. ^ Thomsen M, Mølvig J, Zerbib A, et al. (1988). "The susceptibility to insulin-dependent diabetes mellitus bis associated with C4 allotypes independently of the association with HLA-DQ alleles in HLA-DR3, 4 heterozygotes". Immunogenetics 28 (5): 320–327. doi:10.1007/BF00364230. PMID 3139557. 
6. ^ Jenhani F, Bardi R, Gorgi Y, Ayed K, Jeddi M (1992). "C4 polymorphism in multiplex families with insulin dependent diabetes in the Tunisian population: standard C4 typing methods and RFLP analysis.". J Autoimmun 5 (2): 149–60. PMID 1352685. 
7. ^ Lhotta K, Auinger M, Kronenberg F, Irsigler K, König P (1996). "Polymorphism of complement C4 and susceptibility to IDDM and microvascular complications". Diabetes Care 19 (1): 53–55. 

Further reading

• Hugli TE (1987). "Biochemistry and biology of anaphylatoxins.". Complement 3 (3): 111–27. PMID 3542363. 
• Yu CY (1999). "Molecular genetics of the human MHC complement gene cluster.". Exp. Clin. Immunogenet. 15 (4): 213–30. doi:10.1159/000019075. PMID 10072631. 
• Anderson MJ, Milner CM, Cotton RG, Campbell RD (1992). "The coding sequence of the hemolytically inactive C4A6 allotype of human complement component C4 reveals that a single arginine to tryptophan substitution at beta-chain residue 458 is the likely cause of the defect.". J. Immunol. 148 (9): 2795–802. PMID 1573268. 
• Hessing M, van 't Veer C, Hackeng TM, et al. (1990). "Importance of the alpha 3-fragment of complement C4 for the binding with C4b-binding protein.". FEBS Lett. 271 (1-2): 131–6. doi:10.1016/0014-5793(90)80389-Z. PMID 1699796. 
• Yu CY (1991). "The complete exon-intron structure of a human complement component C4A gene. DNA sequences, polymorphism, and linkage to the 21-hydroxylase gene.". J. Immunol. 146 (3): 1057–66. PMID 1988494. 
• Ghiso J, Saball E, Leoni J, et al. (1990). "Binding of cystatin C to C4: the importance of sense-antisense peptides in their interaction.". Proc. Natl. Acad. Sci. U.S.A. 87 (4): 1288–91. doi:10.1073/pnas.87.4.1288. PMC 53459. PMID 2304899. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=53459. 
• Yu CY, Belt KT, Giles CM, et al. (1987). "Structural basis of the polymorphism of human complement components C4A and C4B: gene size, reactivity and antigenicity.". EMBO J. 5 (11): 2873–81. PMC 1167237. PMID 2431902. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1167237. 
• Speiser PW, White PC (1990). "Structure of the human RD gene: a highly conserved gene in the class III region of the major histocompatibility complex.". DNA 8 (10): 745–51. doi:10.1089/dna.1989.8.745. PMID 2612324. 
• Palsdottir A, Fossdal R, Arnason A, et al. (1987). "Heterogeneity of human C4 gene size. A large intron (6.5 kb) is present in all C4A genes and some C4B genes.". Immunogenetics 25 (5): 299–304. doi:10.1007/BF00404422. PMID 2883116. 
• Kishore N, Shah D, Skanes VM, Levine RP (1989). "The fluid-phase binding of human C4 and its genetic variants, C4A3 and C4B1, to immunoglobulins.". Mol. Immunol. 25 (9): 811–9. doi:10.1016/0161-5890(88)90117-4. PMID 3264881. 
• Chakravarti DN, Campbell RD, Porter RR (1988). "The chemical structure of the C4d fragment of the human complement component C4.". Mol. Immunol. 24 (11): 1187–97. doi:10.1016/0161-5890(87)90165-9. PMID 3696167. 
• Belt KT, Yu CY, Carroll MC, Porter RR (1985). "Polymorphism of human complement component C4.". Immunogenetics 21 (2): 173–80. doi:10.1007/BF00364869. PMID 3838531. 
• Hortin G, Sims H, Strauss AW (1986). "Identification of the site of sulfation of the fourth component of human complement.". J. Biol. Chem. 261 (4): 1786–93. PMID 3944109. 
• Moon KE, Gorski JP, Hugli TE (1981). "Complete primary structure of human C4a anaphylatoxin.". J. Biol. Chem. 256 (16): 8685–92. PMID 6167582. 
• Palsdottir A, Cross SJ, Edwards JH, Carroll MC (1984). "Correlation between a DNA restriction fragment length polymorphism and C4A6 protein.". Nature 306 (5943): 615–6. doi:10.1038/306615a0. PMID 6316164. 
• Belt KT, Carroll MC, Porter RR (1984). "The structural basis of the multiple forms of human complement component C4.". Cell 36 (4): 907–14. doi:10.1016/0092-8674(84)90040-0. PMID 6546707. 
• Carroll MC, Campbell RD, Bentley DR, Porter RR (1984). "A molecular map of the human major histocompatibility complex class III region linking complement genes C4, C2 and factor B.". Nature 307 (5948): 237–41. doi:10.1038/307237a0. PMID 6559257. 
• Carroll MC, Porter RR (1983). "Cloning of a human complement component C4 gene.". Proc. Natl. Acad. Sci. U.S.A. 80 (1): 264–7. doi:10.1073/pnas.80.1.264. PMC 393353. PMID 6572000. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=393353. 
• Whitehead AS, Goldberger G, Woods DE, et al. (1983). "Use of a cDNA clone for the fourth component of human complement (C4) for analysis of a genetic deficiency of C4 in guinea pig.". Proc. Natl. Acad. Sci. U.S.A. 80 (17): 5387–91. doi:10.1073/pnas.80.17.5387. PMC 384261. PMID 6577433. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=384261.