Glycogenin 1 (GYG1) catalyzes its autoglycosylation reaction with UDP-glucose to form oligo (1,4)-alpha-D-glucosyl GYG1 (Moslemi et al. 2010). The oligosaccharide is annotated here as containing four glucose residues. Glycogenin occurs as a homodimer complexed with two molecules of glycogen synthase 1 (GYS1), here in an unphosphorylated (a) form (Roach et al. 2012).