This represents a family of archaeal, bacterial and eukaryotic glycosyl hydrolases, that belong to superfamily GH116. The primary catabolic pathway for glucosylceramide is catalysis by the lysosomal enzyme glucocerebrosidase. In higher eukaryotes, glucosylceramide is the precursor of glycosphingolipids, a complex group of ubiquitous membrane lipids [1]. Mutations in the human protein cause motor-neurone defects in hereditary spastic paraplegia [3]. The catalytic nucleophile, identified in UniProtKB:Q97YG8_SULSO, is a glutamine-335, with the likely acid/base at Asp-442 and the aspartates at Asp-406 and Asp-458 residues also playing a role in the catalysis of glucosides and xylosides that are beta-bound to hydrophobic groups. The family is defined as GH116, which presently includes enzymes with beta-glucosidase, EC:3.2.1.21, beta-xylosidase, EC:3.2.1.37, and glucocerebrosidase EC:3.2.1.45 activity [1,2].

1: Identification of the non-lysosomal glucosylceramidase as beta-glucosidase 2. Boot RG, Verhoek M, Donker-Koopman W, Strijland A, van Marle J, Overkleeft HS, Wennekes T, Aerts JM; J Biol Chem. 2007;282:1305-1312. PMID:17105727

2: A new archaeal beta-glycosidase from Sulfolobus solfataricus: seeding a novel retaining beta-glycan-specific glycoside hydrolase family along with the human non-lysosomal glucosylceramidase GBA2. Cobucci-Ponzano B, Aurilia V, Riccio G, Henrissat B, Coutinho PM, Strazzulli A, Padula A, Corsaro MM, Pieretti G, Pocsfalvi G, Fiume I, Cannio R, Rossi M, Moracci M; J Biol Chem. 2010;285:20691-20703. PMID:20427274

3: Mutations in GBA2 cause autosomal-recessive cerebellar ataxia with spasticity. Hammer MB, Eleuch-Fayache G, Schottlaender LV, Nehdi H, Gibbs JR, Arepalli SK, Chong SB, Hernandez DG, Sailer A, Liu G, Mistry PK, Cai H, Shrader G, Sassi C, Bouhlal Y, Houlden H, Hentati F, Amouri R, Singleton AB; Am J Hum Genet. 2013;92:245-251. PMID:23332917