Purification of rabbit skeletal muscle proteoglycogen: studies on the glucosyl trasnferase activity of polysaccharide-free and bound glycogenin

CARRIZO, MARÍA E.; MIOZZO, MARÍA C.; GOLDRAIJ, A.; CURTINO, JUAN A.

IRL Press at Oxford University Press

Lugar: New York; Año: 1997 vol. 7 p. 571 - 571

roteoglycogen is the end product in the process of glycogen biogenesis. We have purified rabbit muscle proteoglycogen and studied the glucosyltransferase reactions catalyzed by its protein moiety, glycogenin, free or bound to the polysaccharide. The purification strategy involved dissolution of proteoglycogen and cosedimenting membrane vesicles in a Triton X-114/Triton X-45 mixture followed by partition in the aqueous phase, potassium iodide precipitation of accompanying proteins, and washing by high-speed centrifugation. Glycogenin or a proteoglycogen species of an average molecular mass of 200 kDa was isolated by ion-exchange chromatography after the purified proteoglycogen had been subjected to long or short amylolytic digestion, respectively. Besides autoglucosylation from UDPglucose, glycogenin was capable of autogalactosylation from UDP-galactose. The autoglucosylation reaction was not inhibited by the simultaneous glucosylation of the exogenous acceptors N-(maltosy