Uncharacterized glycoside hydrolase family 99-like domain. This family of putative glycoside hydrolases resembles glycosyl hydrolase families 71 and 99 (following the CAZY nomenclature) and may share a similar catalytic site and mechanism. The domain may co-occur with other domains involved in the binding/processing of glycans.

Glycoside hydrolase families 71, 99, and related domains. This superfamily of glycoside hydrolases contains families GH71 and GH99 (following the CAZY nomenclature), as well as other members with undefined function and specificity.

Glycoside hydrolase family 99, an endo-alpha-1,2-mannosidase. This family of glycoside hydrolases 99 (following the CAZY nomenclature) includes endo-alpha-1,2-mannosidase (EC 3.2.1.130), which is an important membrane-associated eukaryotic enzyme involved in the maturation of N-linked glycans. Specifically, it cleaves mannoside linkages internal to N-linked glycan chains by hydrolyzing an alpha-1,2-mannosidic bond between a glucose-substituted mannose and the remainder of the chain. The biological function and significance of the soluble bacterial orthologs, which may have obtained the genes via horizontal transfer, is not clear.

Uncharacterized glycoside hydrolase family 99-like domain. This family of putative glycoside hydrolases resembles glycosyl hydrolase families 71 and 99 (following the CAZY nomenclature) and may share a similar catalytic site and mechanism.

Glycosyl hydrolase family 99. This domain, around 350 residues, is mainly found in some uncharacterized proteins from bacteroides to human. Some proteins in this family, annotated as endo-alpha-mannosidases cleave mannoside linkages internally within an N-linked glycan chain, short circuiting the classical N-glycan biosynthetic pathway. This domain reveals a (beta-alpha)(8) barrel fold in which the catalytic centre is present in a long substrate-binding groove, consistent with cleavage within the N-glycan chain, providing a foundation upon which to develop new enzyme inhibitors targeting the hijacking of N-glycan synthesis in viral disease and cancer.