GM2A

GM2A
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1G13, 1PU5, 1PUB, 1TJJ, 2AF9, 2AG2, 2AG4, 2AG9
Identifiers
Aliases	GM2A, GM2-AP, SAP-3, GM2 ganglioside activator
External IDs	MGI: 95762 HomoloGene: 349 GeneCards: GM2A
Gene ontology Molecular function • lipid transporter activity • phospholipase activator activity • beta-N-acetylgalactosaminidase activity • beta-N-acetylhexosaminidase activity • enzyme activator activity • hydrolase activity • sphingolipid activator protein activity Cellular component • cytoplasm • apical cortex • lysosomal lumen • mitochondrion • hydrogen:potassium-exchanging ATPase complex • cytoplasmic side of plasma membrane • lysosome • extracellular exosome Biological process • positive regulation of hydrolase activity • lipid transport • glycosphingolipid metabolic process • neuromuscular process controlling balance • lipid metabolic process • lipid storage • neurological system process • learning or memory • oligosaccharide catabolic process • ganglioside metabolic process • ganglioside catabolic process • sphingolipid metabolic process • positive regulation of catalytic activity Sources:Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	2760	14667
Ensembl	ENSG00000196743	ENSMUSG00000000594
UniProt	P17900	Q60648
RefSeq (mRNA)	NM_001167607 NM_000405	NM_010299
RefSeq (protein)	NP_000396.2	NP_034429.1
Location (UCSC)	Chr 5: 151.21 – 151.27 Mb	Chr 11: 55.1 – 55.11 Mb
PubMed search	[1]	[2]
Wikidata

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GM2 ganglioside activator also known as GM2A is a protein which in humans is encoded by the GM2A gene.^[3][4]

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.

It was identified as a member of ML domain family of proteins involved in innate immunity and lipid metabolism in the SMART database. .

Regulation

In melanocytic cells GM2A gene expression may be regulated by MITF.^[5]

Clinical significance

Mutations in this gene, inherited in an autosomal recessive pattern, result in GM2-gangliosidosis, AB variant, a rare GM2 gangliosidosis that has symptoms and pathology identical with Tay-Sachs disease and Sandhoff disease.^[6]

GM2A mutations are rarely reported, and the cases that are observed often occur with consanguineous parents or in genetically isolated populations.^[7]

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.

See also

• Gangliosidosis
• Sandhoff disease
• Tay-Sachs disease
• Hexosaminidase
• GM1

References

1. "Human PubMed Reference:".
2. "Mouse PubMed Reference:".
3. Li SC, Nakamura T, Ogamo A, Li YT (November 1979). "Evidence for the presence of two separate protein activators for the enzymic hydrolysis of GM1 and GM2 gangliosides". J. Biol. Chem. 254 (21): 10592–5. PMID 115863.
4. Klima H, Tanaka A, Schnabel D, Nakano T, Schröder M, Suzuki K, Sandhoff K (September 1991). "Characterization of full-length cDNAs and the gene coding for the human GM2 activator protein". FEBS Lett. 289 (2): 260–4. doi:10.1016/0014-5793(91)81084-L. PMID 1915857.
5. Hoek KS, Schlegel NC, Eichhoff OM, et al. (2008). "Novel MITF targets identified using a two-step DNA microarray strategy". Pigment Cell Melanoma Res. 21 (6): 665–76. doi:10.1111/j.1755-148X.2008.00505.x. PMID 19067971.
6. Mahuran DJ (1999-10-08). "Biochemical consequences of mutations causing the GM2 gangliosidoses". Biochimica et Biophysica Acta. 1455 (2–3): 105–138. doi:10.1016/S0925-4439(99)00074-5. PMID 10571007.
7. "Online Mendelian Inheritance in Man". United States National Institute of Health. Retrieved 2009-04-21.

Further reading

• Li SC, Nakamura T, Ogamo A, Li YT (1980). "Evidence for the presence of two separate protein activators for the enzymic hydrolysis of GM1 and GM2 gangliosides". J. Biol. Chem. 254 (21): 10592–5. PMID 115863.
• 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. PMID 1427911.
• Nagarajan S, Chen HC, Li SC, et al. (1992). "Evidence for two cDNA clones encoding human GM2-activator protein". Biochem. J. 282 (3): 807–13. PMC 1130859. PMID 1554364.
• Klima H, Tanaka A, Schnabel D, et al. (1991). "Characterization of full-length cDNAs and the gene coding for the human GM2 activator protein". FEBS Lett. 289 (2): 260–4. doi:10.1016/0014-5793(91)81084-L. PMID 1915857.
• 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. PMID 1915858.
• 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. PMID 2059210.
• 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. PMID 2209618.
• Schröder M, Klima H, Nakano T, et al. (1989). "Isolation of a cDNA encoding the human GM2 activator protein". FEBS Lett. 251 (1–2): 197–200. doi:10.1016/0014-5793(89)81454-1. PMID 2753159.
• 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. PMID 3935131.
• 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. PMID 6724528.
• 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. PMID 6848657.
• 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. PMID 8244332.
• 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. PMID 8288250.
• Klima H, Klein A, van Echten G, et al. (1993). "Over-expression of a functionally active human GM2-activator protein in Escherichia coli". Biochem. J. 292 (2): 571–6. PMC 1134248. PMID 8503891.
• Schepers U, Glombitza G, Lemm T, et al. (1996). "Molecular analysis of a GM2-activator deficiency in two patients with GM2-gangliosidosis AB variant". Am. J. Hum. Genet. 59 (5): 1048–56. PMC 1914821. PMID 8900233.
• 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. PMID 9204879.
• 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. PMID 9217013.
• Schütte CG, Lemm T, Glombitza GJ, Sandhoff K (1998). "Complete localization of disulfide bonds in GM2 activator protein". Protein Sci. 7 (4): 1039–45. doi:10.1002/pro.5560070421. PMC 2143992. PMID 9568910.
• Chen B, Rigat B, Curry C, Mahuran DJ (1999). "Structure of the GM2A gene: identification of an exon 2 nonsense mutation and a naturally occurring transcript with an in-frame deletion of exon 2". Am. J. Hum. Genet. 65 (1): 77–87. doi:10.1086/302463. PMC 1378077. PMID 10364519.
• 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. PMID 10752311.