Muscle glycogen synthesis is normally initiated by the autoglycosylation of glycogenin 1 (GYG1) to form oligo (1,4)-alpha-D-glucosyl GYG1. A missense mutation of GYG1 yields a protein that cannot undergo glucosylation, leading to failure of glycogen synthesis, associated with muscle weakness and other abnormalities (Moslemi et al. 2010).
glycogenin glucosyltransferase activity of mutant GYG1:GYS1-a tetramer [cytosol]
Loss of function of mutant GYG1:GYS1-a tetramer [cytosol]