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 [1].

1: Structural and mechanistic insight into N-glycan processing by endo-α-mannosidase. Thompson AJ, Williams RJ, Hakki Z, Alonzi DS, Wennekes T, Gloster TM, Songsrirote K, Thomas-Oates JE, Wrodnigg TM, Spreitz J, Stütz AE, Butters TD, Williams SJ, Davies GJ; Proc. Natl. Acad. Sci. U.S.A. 109 (3), 781-786 (2012). PMID:22219371