Gene Summary: This gene encodes the alpha 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. Alpha subunit gene mutations lead to Tay-Sachs disease (GM2-gangliosidosis type I).General information above from NCBI
Catalytic activity: Hydrolysis of terminal non-reducing N-acetyl- D-hexosamine residues in N-acetyl-beta-D-hexosaminides.
Subunit structure: There 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.
Domain: The EH domain interacts with Asn-Pro-Phe (NPF) motifs of target proteins (By similarity).
Subcellular location: Lysosome.
Tissue specificity: Highly expressed in testis.
Post-translational: N-linked glycan at Asn-115 consists of Man(3)-GlcNAc(2).
Involvement in disease: GM2-gangliosidosis 1 (GM2G1) [MIM:272800]: An autosomal recessive lysosomal storage disease marked by the accumulation of GM2 gangliosides in the neuronal cells. It is characterized by GM2 gangliosides accumulation in the absence of HEXA activity, leading to neurodegeneration and, in the infantile form, death in early childhood. It exists in several forms: infantile (most common and most severe), juvenile and adult (late-onset). Note=The disease is caused by mutations affecting the gene represented in this entry.
Sequence similarity: Belongs to the glycosyl hydrolase 20 family.
General information above from UniProt
HEXA,Hexosaminidase A,MGC99608,TSD, [human]
Hex-1,Hexa,Hexosaminidase A, [mouse]
Norflus,F. et al., 1996, DNA Cell Biol. 15 (2):89-97.
Kaufman M., et al., 1997, Hum. Mutat. 10:295-300.
Tanaka A., et al., 2003, J. Hum. Genet. 48:571-574.
Chen R., et al., 2009, J. Proteome Res. 8:651-661.
Burkard T.R., et al., 2011, BMC Syst. Biol. 5:17-17.