Meta-Biol

• Pathways

Protein O-linked-mannose beta-1,2-N-acetylglucosaminyltransferase 1 (POMGNT1; CAZy family GT61; MIM:606822) mediates the transfer of N-acetylglucosaminyl (GlcNAc) residues to mannosylated proteins such as mannose-O-serine-dystroglycan (man-O-Ser-DAG1). 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 POMGNT1 (MIM:606822) result in disrupted glycosylation of DAG1 and can cause severe congenital muscular dystrophy-dystroglycanopathies ranging from a severe type A3 (MDDGA3; MIM:253280), through a less severe type B3 (MDDGB3; MIM:613151) to a milder type C3 (MDDGC3; MIM:613157) (Bertini et al. 2011, Wells 2013). Several mutations in POMGNT1 are known (MIM:606822) and mutations causing the severest type A3 include S550N, P493R, R605Vfs*29 (Yoshida et al. 2001), R63* (Taniguchi et al. 2003, Mercuri et al. 2009) and W475* (Godfrey et al. 2007).