Hexosaminidase A (alpha polypeptide), also known as HEXA, is a protein which in humans is encoded by the HEXA gene.[1][2]
Function
Hexosaminidase A is the alpha subunit of the lysosomal enzyme beta-hexosaminidase that, together with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules containing terminal N-acetyl hexosamines. Beta-hexosaminidase is composed of two subunits, alpha (this protein) and beta, which are encoded by separate genes. Both beta-hexosaminidase alpha and beta subunits are members of family 20 of glycosyl hydrolases. Mutations in the alpha or beta subunit genes lead to an accumulation of GM2 ganglioside in neurons and neurodegenerative disorders termed the GM2 gangliosidoses. Alpha subunit gene mutations lead to Tay-Sachs disease (GM2-gangliosidosis type I).[3]
References
- ^ Korneluk RG, Mahuran DJ, Neote K, Klavins MH, O'Dowd BF, Tropak M, Willard HF, Anderson MJ, Lowden JA, Gravel RA (June 1986). "Isolation of cDNA clones coding for the alpha-subunit of human beta-hexosaminidase. Extensive homology between the alpha- and beta-subunits and studies on Tay-Sachs disease". J. Biol. Chem. 261 (18): 8407–13. PMID 3013851.
- ^ Proia RL, Soravia E (April 1987). "Organization of the gene encoding the human beta-hexosaminidase alpha-chain". J. Biol. Chem. 262 (12): 5677–81. PMID 2952641.
- ^ "Entrez Gene: HEXA hexosaminidase A (alpha polypeptide)". http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=3073.
Further reading
- Mahuran DJ (1991). "The biochemistry of HEXA and HEXB gene mutations causing GM2 gangliosidosis.". Biochim. Biophys. Acta 1096 (2): 87–94. PMID 1825792.
- Myerowitz R (1997). "Tay-Sachs disease-causing mutations and neutral polymorphisms in the Hex A gene.". Hum. Mutat. 9 (3): 195–208. doi:10.1002/(SICI)1098-1004(1997)9:3<195::AID-HUMU1>3.0.CO;2-7. PMID 9090523.
- Mahuran DJ (1999). "Biochemical consequences of mutations causing the GM2 gangliosidoses.". Biochim. Biophys. Acta 1455 (2-3): 105–38. PMID 10571007.
- Gilbert F, Kucherlapati R, Creagan RP, et al. (1975). "Tay-Sachs' and Sandhoff's diseases: the assignment of genes for hexosaminidase A and B to individual human chromosomes.". Proc. Natl. Acad. Sci. U.S.A. 72 (1): 263–7. doi:10.1073/pnas.72.1.263. PMID 1054503.
- Trop I, Kaplan F, Brown C, et al. (1993). "A glycine250--> aspartate substitution in the alpha-subunit of hexosaminidase A causes juvenile-onset Tay-Sachs disease in a Lebanese-Canadian family.". Hum. Mutat. 1 (1): 35–9. doi:10.1002/humu.1380010106. PMID 1301189.
- Akalin N, Shi HP, Vavougios G, et al. (1993). "Novel Tay-Sachs disease mutations from China.". Hum. Mutat. 1 (1): 40–6. doi:10.1002/humu.1380010107. PMID 1301190.
- Akerman BR, Zielenski J, Triggs-Raine BL, et al. (1993). "A mutation common in non-Jewish Tay-Sachs disease: frequency and RNA studies.". Hum. Mutat. 1 (4): 303–9. doi:10.1002/humu.1380010407. PMID 1301938.
- Fernandes M, Kaplan F, Natowicz M, et al. (1993). "A new Tay-Sachs disease B1 allele in exon 7 in two compound heterozygotes each with a second novel mutation.". Hum. Mol. Genet. 1 (9): 759–61. doi:10.1093/hmg/1.9.759. PMID 1302612.
- McDowell GA, Mules EH, Fabacher P, et al. (1992). "The presence of two different infantile Tay-Sachs disease mutations in a Cajun population.". Am. J. Hum. Genet. 51 (5): 1071–7. PMID 1307230.
- Whitley CB, Anderson RA, McIvor RS (1992). "Heterozygosity for the "DN allele" (G533-greater than A) of the beta-hexosaminidase alpha subunit gene identified by direct DNA sequencing in a family with the B1 variant of GM2-gangliosidosis.". Neuropediatrics 23 (2): 96–101. doi:10.1055/s-2008-1071320. PMID 1318511.
- Triggs-Raine BL, Mules EH, Kaback MM, et al. (1992). "A pseudodeficiency allele common in non-Jewish Tay-Sachs carriers: implications for carrier screening.". Am. J. Hum. Genet. 51 (4): 793–801. PMID 1384323.
- Hechtman P, Boulay B, De Braekeleer M, et al. (1993). "The intron 7 donor splice site transition: a second Tay-Sachs disease mutation in French Canada.". Hum. Genet. 90 (4): 402–6. PMID 1483696.
- Mules EH, Hayflick S, Miller CS, et al. (1992). "Six novel deleterious and three neutral mutations in the gene encoding the alpha-subunit of hexosaminidase A in non-Jewish individuals.". Am. J. Hum. Genet. 50 (4): 834–41. PMID 1532289.
- Weitz G, Proia RL (1992). "Analysis of the glycosylation and phosphorylation of the alpha-subunit of the lysosomal enzyme, beta-hexosaminidase A, by site-directed mutagenesis.". J. Biol. Chem. 267 (14): 10039–44. PMID 1533633.
- Navon R, Proia RL (1991). "Tay-Sachs disease in Moroccan Jews: deletion of a phenylalanine in the alpha-subunit of beta-hexosaminidase.". Am. J. Hum. Genet. 48 (2): 412–9. PMID 1825014.
- Mules EH, Dowling CE, Petersen MB, et al. (1991). "A novel mutation in the invariant AG of the acceptor splice site of intron 4 of the beta-hexosaminidase alpha-subunit gene in two unrelated American black GM2-gangliosidosis (Tay-Sachs disease) patients.". Am. J. Hum. Genet. 48 (6): 1181–5. PMID 1827945.
- Nakai H, Byers MG, Nowak NJ, Shows TB (1991). "Assignment of beta-hexosaminidase A alpha-subunit to human chromosomal region 15q23----q24.". Cytogenet. Cell Genet. 56 (3-4): 164. doi:10.1159/000133077. PMID 1829032.
- Nishimoto J, Tanaka A, Nanba E, Suzuki K (1991). "Expression of the beta-hexosaminidase alpha subunit gene with the four-base insertion of infantile Jewish Tay-Sachs disease.". J. Biol. Chem. 266 (22): 14306–9. PMID 1830584.
- dos Santos MR, Tanaka A, sá Miranda MC, et al. (1991). "GM2-gangliosidosis B1 variant: analysis of beta-hexosaminidase alpha gene mutations in 11 patients from a defined region in Portugal.". Am. J. Hum. Genet. 49 (4): 886–90. PMID 1832817.
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2gjx: Crystallographic structure of human beta-Hexosaminidase A
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2gk1: X-ray crystal structure of NGT-bound HexA
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