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beta N-acetyl hexosaminidase alpha chain (hexosaminidase-A, HEXA)
Function:
- responsible for the degradation of GM2 gangliosides, & a variety of other molecules containing terminal N-acetyl hexosamines, in the brain & other tissues
- hydrolysis of terminal non-reducing N-acetyl- D-hexosamine residues in N-acetyl-beta-D-hexosaminides
- form B is active against certain oligosaccharides
- form S has no measurable activity
Structure:
- belongs to the glycosyl hydrolase 20 family
- 3 forms of beta-hexosaminidase:
a) hexosaminidase A is a trimer composed of
- one alpha chain,
- one beta-A chain
- one beta-B chain
b) hexosaminidase B is a tetramer of
- two beta-A
- two beta-B chains
c) hexosaminidase S is an homodimer of
- two alpha chains
- two beta chains are derived from the cleavage of a precursor chain
- N-linked glycan at Asn-115 consists of Man(3)-GlcNAc(2)
Compartment: lysosome
Pathology:
- defects in HEXA are the cause of Tay-Sachs disease
Laboratory:
- HEXA gene mutation
- HEXA gene deletion
Related
beta-N-acetylhexosaminidase A in dried blood spot
beta-N-acetylhexosaminidase A in fibroblasts
beta-N-acetylhexosaminidase A in leukocytes
beta-N-acetylhexosaminidase A+beta-N-acetylhexosaminidase A.total in leukocytes
beta-N-acetylhexosaminidase A+beta-N-acetylhexosaminidase A.total in serum
beta-N-acetylhexosaminidase A/beta-N-acetylhexosaminidase A.total in serum
General
glycoprotein
protein subunit
Properties
SIZE: entity length = 529 aa
MW = 61 kD
COMPARTMENT: lysosome
MOTIF: signal sequence {1-22}
cysteine residue {C58}
MODIFICATION: cysteine residue {C104}
cysteine residue {C104}
MODIFICATION: cysteine residue {C58}
N-glycosylation site {N115}
N-glycosylation site {N157}
cysteine residue {C277}
MODIFICATION: cysteine residue {C328}
N-glycosylation site {N295}
glutamate residue {E323}
cysteine residue {C328}
MODIFICATION: cysteine residue {C277}
cysteine residue {C505}
MODIFICATION: cysteine residue {C522}
cysteine residue {C522}
MODIFICATION: cysteine residue {C505}
Database Correlations
OMIM correlations
MORBIDMAP 606869
UniProt P06865
KEGG correlations
ENZYME 3.2.1.52
References
- UniProt :accession P06865
- HEXAdb; HEXA mutation database
http://www.hexdb.mcgill.ca/?Topic=HEXAdb
- Genedis; note=Tay Sachs disease website
http://life2.tau.ac.il/Genedis/Tables/Tay_Sachs/tay_sachs.html
- GeneReviews
https://www.genecards.org/cgi-bin/carddisp.pl?gene=HEXA
Component-of
beta N-acetylhexosaminidase