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:
  • hexosaminidase A is a trimer composed of
    • one alpha chain,
    • one beta-A chain
    • one beta-B chain
  • hexosaminidase B is a tetramer of
    • two beta-A
    • two beta-B chains
  • 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

More general terms

• glycoprotein
• protein subunit

Component of

• beta N-acetylhexosaminidase

Database

• UniProt: http://www.uniprot.org/uniprot/P06865.html
• OMIM: https://mirror.omim.org/entry/272800
• OMIM: https://mirror.omim.org/entry/606869