title: Contraction-mediated inactivation of glycogen synthase is accompanied by inactivation of glycogen synthase phosphatase in human skeletal muscle.
abstract: Activities of glycogen synthase (GS) and GS phosphatase were determined on human muscle biopsies before and after isometric contraction at 2/3 maximal voluntary force. Total GS activity did not change during contraction (4.92 +/- 0.70 at rest versus 5.00 +/- 0.42 mmol/min per kg dry wt.; mean +/- S.E.M.), whereas both the active form of GS and the ratio of active form to total GS decreased by approximately 35% (P less than 0.01). GS phosphatase was inactivated in all subjects by an average of 39%, from 5.95 +/- 1.30 to 3.63 +/- 0.97 mmol/min per kg dry wt. (P less than 0.01). It is suggested that at least part of the contraction-induced inactivation of GS is due to an inactivation of GS phosphatase.
authors.affiliation: Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, AZ 85016.
authors.forename: Y
authors.initials: Y
authors.lastname: Kida
authors.forename: A
authors.initials: A
authors.lastname: Katz
authors.forename: A D
authors.initials: AD
authors.lastname: Lee
authors.forename: D M
authors.initials: DM
authors.lastname: Mott
mesh_terms: D000328:Adult; D006006:Glycogen Synthase / Q000378:metabolism*; D006007:Glycogen-Synthase-D Phosphatase / Q000378:metabolism*; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D009119:Muscle Contraction; D009132:Muscles / Q000201:enzymology*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*
chemical_list: D006006:Glycogen Synthase; D010749:Phosphoprotein Phosphatases; D006007:Glycogen-Synthase-D Phosphatase