GlcNAc-GlcA-GlcNAc Beta-hexosaminidase A (BHEXA) cleaves the terminal GalNAc from small HA fragments Authored: Jassal, B, 2012-03-16 Beta-hexosaminidase A (bHEXA) cleaves the terminal N-acetyl galactosamine (GalNAc) from glucosaminoglycans (GAGs) and any other molecules containing a terminal GalNAc. There are two forms of bHEX: hexosaminidase A and B. The A form is a trimer of the subunits alpha, beta A and beta B. The B form is a tetramer of 2 beta A and 2 beta B subunits (O'Dowd et al. 1988). Defects in the two subunits cause lysosomal storage diseases marked by the accumulation of GM2 gangliosides in neuronal cells. Defects in the alpha subunits are the cause of GM2-gangliosidosis type 1 (GM2G1) (MIM:272800), also known as Tay-Sachs disease (Nakano et al. 1988). Defects in the beta subunits are the cause of GM2-gangliosidosis type 2 (GM2G2) (MIM:268800), also known as Sandhoff disease (Banerjee et al. 1991). EC Number: 3.2.1.52 Edited: Jassal, B, 2012-03-16 Pubmed1720305 Pubmed2970528 Pubmed2971395 Reactome Database ID Release 432162225 Reactome, http://www.reactome.org ReactomeREACT_121200 Reviewed: D'Eustachio, P, 2012-03-28