HEXB

Hexosaminidase B (beta polypeptide)
PDB rendering based on 1nou.
Available structures PDB Ortholog search: PDBe, RCSB List of PDB id codes 1NOU​, 1NOW​, 1NP0​, 1O7A​, 1QBD​, 2GJX​, 2GK1​, 3LMY​
Identifiers
Symbols	HEXB ; ENC-1AS; HEL-248
External IDs	OMIM: 606873 MGI: 96074 HomoloGene: 437 ChEMBL: 5877 GeneCards: HEXB Gene
EC number	3.2.1.52
Gene ontology Molecular function • beta-N-acetylhexosaminidase activity • acetylglucosaminyltransferase activity • protein homodimerization activity • protein heterodimerization activity Cellular component • acrosomal vesicle • membrane • azurophil granule • lysosomal lumen • extracellular exosome Biological process • skeletal system development • carbohydrate metabolic process • sphingolipid metabolic process • glycosphingolipid metabolic process • ganglioside catabolic process • cellular calcium ion homeostasis • lysosome organization • penetration of zona pellucida • sensory perception of sound • locomotory behavior • male courtship behavior • regulation of cell shape • phospholipid biosynthetic process • oligosaccharide catabolic process • lipid storage • glycosaminoglycan metabolic process • chondroitin sulfate metabolic process • chondroitin sulfate catabolic process • hyaluronan metabolic process • hyaluronan catabolic process • keratan sulfate metabolic process • keratan sulfate catabolic process • myelination • astrocyte cell migration • cellular protein metabolic process • small molecule metabolic process • positive regulation of transcription from RNA polymerase II promoter • oogenesis • neuromuscular process controlling balance Sources: Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	3074	15212
Ensembl	ENSG00000049860	ENSMUSG00000021665
UniProt	P07686	P20060
RefSeq (mRNA)	NM_000521	NM_010422
RefSeq (protein)	NP_000512	NP_034552
Location (UCSC)	Chr 5: 74.64 – 74.72 Mb	Chr 13: 97.18 – 97.2 Mb
PubMed search

Beta-hexosaminidase subunit beta is an enzyme that in humans is encoded by the HEXB gene.^[1][2][3]

Hexosaminidase B is the beta 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 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. Beta subunit gene mutations lead to Sandhoff disease (GM2-gangliosidosis type II).^[3]

References

1. O'Dowd BF, Quan F, Willard HF, Lamhonwah AM, Korneluk RG, Lowden JA, Gravel RA, Mahuran DJ (Apr 1985). "Isolation of cDNA clones coding for the beta subunit of human beta-hexosaminidase". Proc Natl Acad Sci U S A 82 (4): 1184–8. doi:10.1073/pnas.82.4.1184. PMC 397219. PMID 2579389.
2. Korneluk RG, Mahuran DJ, Neote K, Klavins MH, O'Dowd BF, Tropak M, Willard HF, Anderson MJ, Lowden JA, Gravel RA (Jul 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.
3. "Entrez Gene: HEXB hexosaminidase B (beta polypeptide)".

Further reading

• Mahuran DJ (1991). "The biochemistry of HEXA and HEXB gene mutations causing GM2 gangliosidosis.". Biochim. Biophys. Acta 1096 (2): 87–94. doi:10.1016/0925-4439(91)90044-A. PMID 1825792.
• Mahuran DJ (1999). "Biochemical consequences of mutations causing the GM2 gangliosidoses.". Biochim. Biophys. Acta 1455 (2-3): 105–38. doi:10.1016/S0925-4439(99)00074-5. 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. PMC 432284. PMID 1054503.
• McInnes B, Potier M, Wakamatsu N, et al. (1992). "An unusual splicing mutation in the HEXB gene is associated with dramatically different phenotypes in patients from different racial backgrounds.". J. Clin. Invest. 90 (2): 306–14. doi:10.1172/JCI115863. PMC 443103. PMID 1386607.
• Bolhuis PA, Bikker H (1993). "Deletion of the 5'-region in one or two alleles of HEXB in 15 out of 30 patients with Sandhoff disease.". Hum. Genet. 90 (3): 328–9. doi:10.1007/bf00220096. PMID 1487253.
• Wakamatsu N, Kobayashi H, Miyatake T, Tsuji S (1992). "A novel exon mutation in the human beta-hexosaminidase beta subunit gene affects 3' splice site selection.". J. Biol. Chem. 267 (4): 2406–13. PMID 1531140.
• Banerjee P, Siciliano L, Oliveri D, et al. (1992). "Molecular basis of an adult form of beta-hexosaminidase B deficiency with motor neuron disease.". Biochem. Biophys. Res. Commun. 181 (1): 108–15. doi:10.1016/S0006-291X(05)81388-9. PMID 1720305.
• Boose JA, Tifft CJ, Proia RL, Myerowitz R (1992). "Synthesis of a human lysosomal enzyme, beta-hexosaminidase B, using the baculovirus expression system.". Protein Expr. Purif. 1 (2): 111–20. doi:10.1016/1046-5928(90)90003-H. PMID 1967020.
• Mahuran DJ (1990). "Characterization of human placental beta-hexosaminidase I2. Proteolytic processing intermediates of hexosaminidase A.". J. Biol. Chem. 265 (12): 6794–9. PMID 2139028.
• Neote K, McInnes B, Mahuran DJ, Gravel RA (1990). "Structure and distribution of an Alu-type deletion mutation in Sandhoff disease.". J. Clin. Invest. 86 (5): 1524–31. doi:10.1172/JCI114871. PMC 296899. PMID 2147027.
• Neote K, Brown CA, Mahuran DJ, Gravel RA (1991). "Translation initiation in the HEXB gene encoding the beta-subunit of human beta-hexosaminidase.". J. Biol. Chem. 265 (34): 20799–806. PMID 2147427.
• Dlott B, d'Azzo A, Quon DV, Neufeld EF (1990). "Two mutations produce intron insertion in mRNA and elongated beta-subunit of human beta-hexosaminidase.". J. Biol. Chem. 265 (29): 17921–7. PMID 2170400.
• Nakano T, Suzuki K (1989). "Genetic cause of a juvenile form of Sandhoff disease. Abnormal splicing of beta-hexosaminidase beta chain gene transcript due to a point mutation within intron 12.". J. Biol. Chem. 264 (9): 5155–8. PMID 2522450.
• Hubbes M, Callahan J, Gravel R, Mahuran D (1989). "The amino-terminal sequences in the pro-alpha and -beta polypeptides of human lysosomal beta-hexosaminidase A and B are retained in the mature isozymes.". FEBS Lett. 249 (2): 316–20. doi:10.1016/0014-5793(89)80649-0. PMID 2525487.
• Bikker H, van den Berg FM, Wolterman RA, et al. (1989). "Demonstration of a Sandhoff disease-associated autosomal 50-kb deletion by field inversion gel electrophoresis.". Hum. Genet. 81 (3): 287–8. doi:10.1007/BF00279006. PMID 2921040.
• Bolhuis PA, Oonk JG, Kamp PE, et al. (1987). "Ganglioside storage, hexosaminidase lability, and urinary oligosaccharides in adult Sandhoff's disease.". Neurology 37 (1): 75–81. doi:10.1212/wnl.37.1.75. PMID 2948136.
• Proia RL (1988). "Gene encoding the human beta-hexosaminidase beta chain: extensive homology of intron placement in the alpha- and beta-chain genes.". Proc. Natl. Acad. Sci. U.S.A. 85 (6): 1883–7. doi:10.1073/pnas.85.6.1883. PMC 279885. PMID 2964638.
• Mahuran DJ, Neote K, Klavins MH, et al. (1988). "Proteolytic processing of pro-alpha and pro-beta precursors from human beta-hexosaminidase. Generation of the mature alpha and beta a beta b subunits.". J. Biol. Chem. 263 (10): 4612–8. PMID 2965147.