O-mannosylation in mammalian cells.
The O-mannosyl glycan is present in a limited number of glycoproteins of brain, nerve, and skeletal muscle. alpha-Dystroglycan is one of the O-mannosylated proteins and is a central component of the dystrophin-glycoprotein complex that has been shown to be related to the onset of muscular dystrophy. We have identified and characterized glycosyltransferases, protein O-mannose beta1,2-N-acetylglucosaminyltransferase (POMGnT1) and protein O-mannosyltransferase 1 (POMT1), involved in the biosynthesis of O-mannosyl glycans. We subsequently found that loss of function of the POMGnT1 gene is responsible for muscle-eye-brain disease (MEB). It has also been reported that the POMT1 gene is responsible for Walker-Warburg syndrome (WWS). MEB and WWS are autosomal recessive disorders characterized by congenital muscular dystrophies with neuronal migration disorders. Therefore, the ability to assay enzyme activities of mammalian O-mannosylation would facilitate progress in the identification of other O-mannosylated proteins, the elucidation of their functional roles, and the understanding of muscular dystrophies. This protocol describes assay methods for the mammalian POMT and POMGnT.
Endo
Tamao
T
Glycobiology Research Group, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
Manya
Hiroshi
H
D000818:Animals; D001923:Brain Chemistry; D002478:Cells, Cultured; D006801:Humans; D007425:Intracellular Membranes / Q000201:enzymology; D008322:Mammals / Q000378:metabolism*; D008358:Mannose / Q000378:metabolism*; D008364:Mannosyltransferases / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D008967:Molecular Biology / Q000379:methods*; D017351:N-Acetylglucosaminyltransferases / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344
D008364:Mannosyltransferases; D017351:N-Acetylglucosaminyltransferases; C443106:protein O-mannose beta-1,2-N-acetylglucosaminyltransferase; C082696:protein O-mannosyltransferase; D008358:Mannose