C4A
O Complemento C4-A é uma proteína que em humanos é codificada pelo gene C4A.[3]
Função
Este gene codifica a forma ácida do fator 4 do complemento, parte da via clássica de ativação. A proteína é expressa como um precursor de cadeia única que é clivada proteoliticamente num trímero de cadeias alfa, beta e gama antes da secreção. O trímero fornece uma superfície para interação entre o complexo antígeno-anticorpo e outros componentes do complemento. A cadeia alfa pode ser clivada para liberar a anafilatoxina C4, um mediador da inflamação local. A deficiência dessa proteína está associada ao lúpus eritematoso sistêmico e ao diabetes mellitus tipo I.[4][5][6][7][8][9] O excesso de produção está associado à esquizofrenia e transtorno bipolar com psicose.[10] Este gene localiza-se na região do complexo principal de histocompatibilidade (MHC) de classe III no cromossomo 6. Existem haplótipos variados desse aglomerado de genes, de modo que os indivíduos podem ter 1, 2 ou 3 cópias desse gene.[3]
Referências
- ↑ «Doenças geneticamente associadas a C4A ver/editar referências no wikidata»
- ↑ «Human PubMed Reference:»
- ↑ a b «Entrez Gene: C4A complement component 4A (Rodgers blood group)»
- ↑ Dawkins RL, Uko G, Christiansen FT, Kay PH (setembro de 1983). «Low C4 concentrations in insulin dependent diabetes mellitus». British Medical Journal. 287 (6395). 839 páginas. PMC 1549128
. PMID 6412852. doi:10.1136/bmj.287.6395.839-b
- ↑ Vergani D, Johnston C, B-Abdullah N, Barnett AH (março de 1983). «Low serum C4 concentrations: an inherited predisposition to insulin dependent diabetes?». British Medical Journal. 286 (6369): 926–8. PMC 1547358. PMID 6403137. doi:10.1136/bmj.286.6369.926
- ↑ Mijovic CH, Fletcher JA, Bradwell AR, Barnett AH (outubro de 1987). «Low C4 levels in type 1 (insulin-dependent) diabetes». Diabetologia. 30 (10). 824 páginas. PMID 3428499. doi:10.1007/bf00275752
- ↑ Thomsen M, Mølvig J, Zerbib A, de Preval C, Abbal M, Dugoujon JM, Ohayon E, Svejgaard A, Cambon-Thomsen A, Nerup J (1988). «The susceptibility to insulin-dependent diabetes mellitus is associated with C4 allotypes independently of the association with HLA-DQ alleles in HLA-DR3,4 heterozygotes». Immunogenetics. 28 (5): 320–7. PMID 3139557. doi:10.1007/BF00364230
- ↑ Jenhani F, Bardi R, Gorgi Y, Ayed K, Jeddi M (abril de 1992). «C4 polymorphism in multiplex families with insulin dependent diabetes in the Tunisian population: standard C4 typing methods and RFLP analysis». Journal of Autoimmunity. 5 (2): 149–60. PMID 1352685. doi:10.1016/0896-8411(92)90196-w
- ↑ 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. doi:10.2337/diacare.19.1.53
- ↑ Sharma, RP. «C4A mRNA expression in PBMCs predicts the presence and severity of delusions in schizophrenia and bipolar disorder with psychosis.». Schizophr Res. PMID 29449061. doi:10.1016/j.schres.2018.01.018
Leitura adicional
- 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». Experimental and Clinical Immunogenetics. 15 (4): 213–30. PMID 10072631. doi:10.1159/000019075
- Anderson MJ, Milner CM, Cotton RG, Campbell RD (maio de 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». Journal of Immunology. 148 (9): 2795–802. PMID 1573268
- Hessing M, van 't Veer C, Hackeng TM, Bouma BN, Iwanaga S (outubro de 1990). «Importance of the alpha 3-fragment of complement C4 for the binding with C4b-binding protein». FEBS Letters. 271 (1-2): 131–6. PMID 1699796. doi:10.1016/0014-5793(90)80389-Z
- Yu CY (fevereiro de 1991). «The complete exon-intron structure of a human complement component C4A gene. DNA sequences, polymorphism, and linkage to the 21-hydroxylase gene». Journal of Immunology. 146 (3): 1057–66. PMID 1988494
- Ghiso J, Saball E, Leoni J, Rostagno A, Frangione B (fevereiro de 1990). «Binding of cystatin C to C4: the importance of sense-antisense peptides in their interaction». Proceedings of the National Academy of Sciences of the United States of America. 87 (4): 1288–91. PMC 53459. PMID 2304899. doi:10.1073/pnas.87.4.1288
- Yu CY, Belt KT, Giles CM, Campbell RD, Porter RR (novembro de 1986). «Structural basis of the polymorphism of human complement components C4A and C4B: gene size, reactivity and antigenicity». The EMBO Journal. 5 (11): 2873–81. PMC 1167237. PMID 2431902
- Speiser PW, White PC (dezembro de 1989). «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. PMID 2612324. doi:10.1089/dna.1989.8.745
- Palsdottir A, Fossdal R, Arnason A, Edwards JH, Jensson O (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. PMID 2883116. doi:10.1007/BF00404422
- Kishore N, Shah D, Skanes VM, Levine RP (setembro de 1988). «The fluid-phase binding of human C4 and its genetic variants, C4A3 and C4B1, to immunoglobulins». Molecular Immunology. 25 (9): 811–9. PMID 3264881. doi:10.1016/0161-5890(88)90117-4
- Chakravarti DN, Campbell RD, Porter RR (novembro de 1987). «The chemical structure of the C4d fragment of the human complement component C4». Molecular Immunology. 24 (11): 1187–97. PMID 3696167. doi:10.1016/0161-5890(87)90165-9
- Belt KT, Yu CY, Carroll MC, Porter RR (1985). «Polymorphism of human complement component C4». Immunogenetics. 21 (2): 173–80. PMID 3838531. doi:10.1007/BF00364869
- Hortin G, Sims H, Strauss AW (fevereiro de 1986). «Identification of the site of sulfation of the fourth component of human complement». The Journal of Biological Chemistry. 261 (4): 1786–93. PMID 3944109
- Moon KE, Gorski JP, Hugli TE (agosto de 1981). «Complete primary structure of human C4a anaphylatoxin». The Journal of Biological Chemistry. 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. PMID 6316164. doi:10.1038/306615a0
- Belt KT, Carroll MC, Porter RR (abril de 1984). «The structural basis of the multiple forms of human complement component C4». Cell. 36 (4): 907–14. PMID 6546707. doi:10.1016/0092-8674(84)90040-0
- 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. PMID 6559257. doi:10.1038/307237a0
- Carroll MC, Porter RR (janeiro de 1983). «Cloning of a human complement component C4 gene». Proceedings of the National Academy of Sciences of the United States of America. 80 (1): 264–7. PMC 393353. PMID 6572000. doi:10.1073/pnas.80.1.264
- Whitehead AS, Goldberger G, Woods DE, Markham AF, Colten HR (setembro de 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». Proceedings of the National Academy of Sciences of the United States of America. 80 (17): 5387–91. PMC 384261. PMID 6577433. doi:10.1073/pnas.80.17.5387
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