Glycogenin 2 (GYG2) catalyzes its autoglycosylation reaction with UDP-glucose to form oligo (1,4)-alpha-D-glucosyl GYG2 (Mu et al. 1997). The oligosaccharide is annotated here as containing four glucose residues. Glycogenin occurs as a homodimer complexed with two molecules of glycogen synthase 1 (GYS2), here in a unphosphorylated (a) form (Roach et al. 2012).