N-terminal catalytic domain of class II alpha-mannosidases and similar proteins; glycoside hydrolase family 38 (GH38). Alpha-mannosidases (EC 3.2.1.24) are extensively found in eukaryotes and play important roles in the processing of newly formed N-glycans and in degradation of mature glycoproteins. A deficiency of this enzyme causes the lysosomal storage disease alpha-mannosidosis. Many bacterial and archaeal species also possess putative alpha-mannosidases, but their activity and specificity is largely unknown. Based on different functional characteristics and sequence homology, alpha-mannosidases have been organized into two classes (class I, belonging to glycoside hydrolase family 47, and class II, belonging to glycoside hydrolase family 38). Members of this family corresponds to class II alpha-mannosidases (alphaMII), which contain intermediate Golgi alpha-mannosidases II, acidic lysosomal alpha-mannosidases, animal sperm and epididymal alpha -mannosidases, neutral ER/cytosolic alpha-mannosidases, and some putative prokaryotic alpha-mannosidases. AlphaMII possess a-1,3, a-1,6, and a-1,2 hydrolytic activity, and catalyzes the degradation of N-linked oligosaccharides. The N-terminal catalytic domain of alphaMII adopts a structure consisting of parallel 7-stranded beta/alpha barrel. Members in this family are retaining glycosyl hydrolases of family GH38 that employs a two-step mechanism involving the formation of a covalent glycosyl enzyme complex. Two carboxylic acids positioned within the active site act in concert: one as a catalytic nucleophile and the other as a general acid/base catalyst.
Alpha mannosidase, middle domain. Members of this entry belong to the glycosyl hydrolase family 38, This domain, which is found in the central region adopts a structure consisting of three alpha helices, in an immunoglobulin/albumin-binding domain-like fold. The domain is predominantly found in the enzyme alpha-mannosidase.
Alpha mannosidase middle domain. Members of this family adopt a structure consisting of three alpha helices, in an immunoglobulin/albumin-binding domain-like fold. They are predominantly found in the enzyme alpha-mannosidase.
Glycosyl hydrolases family 38 C-terminal beta sandwich domain. This domain is found at the C-terminal end of various glycosyl hydrolases belonging to family 38. The domain has a beta sandwich fold.