Characterization of Glucose-6-phosphate-dependent Glycogen Synthase from Dictyostelium discoideum

SUMMARY: Glucose-6-phosphate-dependent glycogen synthase from Dictyostelium discoideum was purified and characterized. Several nucleoside phosphates inhibited enzyme activity at their physiological concentrations (about 10-4M). Glucose 6-phosphate and UDPglucose released these inhibitions at levels above their physiological concentrations. Unless compartmentation is invoked, experiments suggest that the glucose-6-phosphate-dependent enzyme is inactive in vivo.