GM2 ganglioside activator also known as GM2A is a protein which in humans is encoded by the GM2Agene.[5][6]
Function
The protein encoded by this gene is a small glycolipid transport protein which acts as a substrate specific co-factor for the lysosomal enzyme β-hexosaminidase A. β-hexosaminidase A, together with GM2 ganglioside activator, catalyzes the degradation of the ganglioside GM2, and other molecules containing terminal N-acetyl hexosamines.
GM2A is a lipid transfer protein that stimulates the enzymatic processing of gangliosides, and also T-cell activation through lipid presentation. This protein binds molecules of ganglioside GM2, extracts them from membranes, and presents them to beta-hexosaminidase A for cleavage of N-acetyl-D-galactosamine and conversion to GM3.
GM2A mutations are rarely reported, and the cases that are observed often occur with consanguineous parents or in genetically isolated populations.[9]
Because AB variant is so rarely diagnosed, even in infants, it is likely that most mutations of GM2A are fatal in the fetus in homozygotes and genetic compounds, and thus are never observed clinically.
Xie B, Kennedy JL, McInnes B, et al. (1992). "Identification of a processed pseudogene related to the functional gene encoding the GM2 activator protein: localization of the pseudogene to human chromosome 3 and the functional gene to human chromosome 5". Genomics. 14 (3): 796–8. doi:10.1016/S0888-7543(05)80190-9. PMID1427911.
Schröder M, Schnabel D, Suzuki K, Sandhoff K (1991). "A mutation in the gene of a glycolipid-binding protein (GM2 activator) that causes GM2-gangliosidosis variant AB". FEBS Lett. 290 (1–2): 1–3. doi:10.1016/0014-5793(91)81211-P. PMID1915858. S2CID26669859.
Xie B, McInnes B, Neote K, et al. (1991). "Isolation and expression of a full-length cDNA encoding the human GM2 activator protein". Biochem. Biophys. Res. Commun. 177 (3): 1217–23. doi:10.1016/0006-291X(91)90671-S. PMID2059210.
Fürst W, Schubert J, Machleidt W, et al. (1990). "The complete amino-acid sequences of human ganglioside GM2 activator protein and cerebroside sulfate activator protein". Eur. J. Biochem. 192 (3): 709–14. doi:10.1111/j.1432-1033.1990.tb19280.x. PMID2209618.
Burg J, Banerjee A, Sandhoff K (1986). "Molecular forms of GM2-activator protein. A study on its biosynthesis in human skin fibroblasts". Biol. Chem. Hoppe-Seyler. 366 (9): 887–91. doi:10.1515/bchm3.1985.366.2.887. PMID3935131.
Banerjee A, Burg J, Conzelmann E, et al. (1984). "Enzyme-linked immunosorbent assay for the ganglioside GM2-activator protein. Screening of normal human tissues and body fluids, of tissues of GM2 gangliosidosis, and for its subcellular localization". Hoppe-Seyler's Z. Physiol. Chem. 365 (3): 347–56. doi:10.1515/bchm2.1984.365.1.347. PMID6724528.
Hirabayashi Y, Li YT, Li SC (1983). "The protein activator specific for the enzymic hydrolysis of GM2 ganglioside in normal human brain and brains of three types of GM2 gangliosidosis". J. Neurochem. 40 (1): 168–75. doi:10.1111/j.1471-4159.1983.tb12667.x. PMID6848657. S2CID33699881.
Schröder M, Schnabel D, Hurwitz R, et al. (1994). "Molecular genetics of GM2-gangliosidosis AB variant: a novel mutation and expression in BHK cells". Hum. Genet. 92 (5): 437–40. doi:10.1007/BF00216446. PMID8244332. S2CID21839371.
Heng HH, Xie B, Shi XM, et al. (1994). "Refined mapping of the GM2 activator protein (GM2A) locus to 5q31.3-q33.1, distal to the spinal muscular atrophy locus". Genomics. 18 (2): 429–31. doi:10.1006/geno.1993.1491. PMID8288250.
Rigat B, Wang W, Leung A, Mahuran DJ (1997). "Two mechanisms for the recapture of extracellular GM2 activator protein: evidence for a major secretory form of the protein". Biochemistry. 36 (27): 8325–31. doi:10.1021/bi970571c. PMID9204879.
Yadao F, Hechtman P, Kaplan F (1997). "Formation of a ternary complex between GM2 activator protein, GM2 ganglioside and hexosaminidase A". Biochim. Biophys. Acta. 1340 (1): 45–52. doi:10.1016/S0167-4838(97)00027-7. PMID9217013.
Jinnai H, Nakamura S (2000). "Characterization of phospholipase D activation by GM2 activator in a cell-free system". Kobe Journal of Medical Sciences. 45 (3–4): 181–90. PMID10752311.