POMT1:POMT2 transfers Man from Dol-P-Man to DAG1(30-653)

Stable Identifier
Reaction [transition]
Homo sapiens
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Co-expression of both protein O-mannosyl-transferases 1 and 2 (POMT1 and POMT2; CAZy family GT39) is necessary for enzyme activity (Manya et al. 2004), that is mediating the transfer of mannosyl residues to the hydroxyl group of serine or threonine residues of proteins such as alpha-dystroglycan (DAG1; MIM:128239). This process occurs in the ER lumen and both POMT isozymes are ER membrane residents. DAG1 is a cell surface protein that plays an important role in the assembly of the extracellular matrix in muscle, brain, and peripheral nerves by linking the basal lamina to cytoskeletal proteins. Defects in POMT2 (MIM:607439) results in defective glycosylation of DAG1 and can cause severe congenital muscular dystrophy dystroglycanopathies ranging from a severe type A, MDDGA2 (brain and eye abnormalities; MIM:613150), through a less severe type B, MDDGB2 (congenital form with mental retardation; MIM:613156) to a milder type C, MDDGC2 (limb girdle form; MIM:603158) (Bertini et al. 2011, Wells 2013).

Literature References
PubMed ID Title Journal Year
14699049 Demonstration of mammalian protein O-mannosyltransferase activity: coexpression of POMT1 and POMT2 required for enzymatic activity

Yoshida, A, Jigami, Y, Endo, T, Chiba, Y, Chiba, A, Manya, H, Wang, X, Margolis, RU

Proc. Natl. Acad. Sci. U.S.A. 2004
23329833 The o-mannosylation pathway: glycosyltransferases and proteins implicated in congenital muscular dystrophy

Wells, L

J. Biol. Chem. 2013
22172424 Congenital muscular dystrophies: a brief review

Gualandi, F, D'Amico, A, Petrini, S, Bertini, E

Semin Pediatr Neurol 2011
Catalyst Activity

dolichyl-phosphate-mannose-protein mannosyltransferase activity of POMT1:POMT2 [endoplasmic reticulum membrane]

Orthologous Events
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