MGP Database

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MGP001432

UniProt Annotations

Entry Information
Gene Namehexosaminidase B (beta polypeptide)
Protein EntryHEXB_HUMAN
UniProt IDP07686
SpeciesHuman
Comments
Comment typeDescription
Catalytic ActivityHydrolysis of terminal non-reducing N-acetyl- D-hexosamine residues in N-acetyl-beta-D-hexosaminides.
DiseaseGM2-gangliosidosis 2 (GM2G2) [MIM:268800]: An autosomal recessive lysosomal storage disease marked by the accumulation of GM2 gangliosides in the neuronal cells. Clinically indistinguishable from GM2-gangliosidosis type 1, presenting startle reactions, early blindness, progressive motor and mental deterioration, macrocephaly and cherry-red spots on the macula. {ECO:0000269|PubMed:1531140, ECO:0000269|PubMed:1720305, ECO:0000269|PubMed:7557963, ECO:0000269|PubMed:7626071, ECO:0000269|PubMed:7633435, ECO:0000269|PubMed:8357844, ECO:0000269|PubMed:8950198, ECO:0000269|PubMed:9401004, ECO:0000269|PubMed:9694901, ECO:0000269|PubMed:9856491}. Note=The disease is caused by mutations affecting the gene represented in this entry.
FunctionResponsible for the degradation of GM2 gangliosides, and a variety of other molecules containing terminal N-acetyl hexosamines, in the brain and other tissues.
PtmN-linked glycans at Asn-142 and Asn-190 consist of Man(3)- GlcNAc(2) and Man(5 to 7)-GlcNAc(2), respectively. {ECO:0000269|PubMed:11447134, ECO:0000269|PubMed:12754519, ECO:0000269|PubMed:19159218}.
PtmThe beta-A and beta-B chains are produced by proteolytic processing of the precursor beta chain.
Sequence CautionSequence=AAA51828.1; Type=Frameshift; Positions=21; Evidence={ECO:0000305}; Sequence=AAA68620.1; Type=Erroneous initiation; Evidence={ECO:0000305};
SimilarityBelongs to the glycosyl hydrolase 20 family. {ECO:0000305}.
Subcellular LocationLysosome.
SubunitThere are 3 forms of beta-hexosaminidase: hexosaminidase A is a trimer composed of one subunit alpha, one subunit beta chain A and one subunit beta chain B; hexosaminidase B is a tetramer of two subunit beta chains A and two subunit beta chains B; hexosaminidase S is a homodimer of two alpha subunits. The two beta chains are derived from the cleavage of the beta subunit.
Web ResourceName=HEXBdb; Note=HEXB mutation database; URL="http://www.hexdb.mcgill.ca/?Topic=HEXBdb";
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