Relationships between dephosphorylation and D to I conversion of rabbit skeletal muscle glycogen synthase.
The relationship between dephosphorylation and D to I conversion of skeletal muscle glycogen synthase by synthase phosphatase was investigated using synthase preparations containing 1 to 3 mol of 32P/mol of subunit (90,000 g). Dephosphorylation was analyzed in terms of 32P release from the trypsin-sensitive and trypsin-insensitive phosphorylation regions of synthase. With synthase containing 1 to 2 mol of 32P/90,000 g, dephosphorylation of the trypsin-insensitive region correlated closely with D to I conversion and was more rapid than dephosphorylation of the trypsin-sensitive region. Synthase containing 3 mol of 32P/90,000 g was a relatively poor substrate for the phosphatase since dephosphorylation of both regions, as well as D to I conversion, was slow. With this species of synthase, glucose-6-P (0.1 mM) increased the rates of D to I conversion and dephosphorylation of trypsin-insensitive region. It is concluded that dephosphorylation of the trypsin-insensitive region is responsible for the conversion of synthase D to I.
D000818:Animals; D006006:Glycogen Synthase / Q000378:metabolism*; D006007:Glycogen-Synthase-D Phosphatase / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D009132:Muscles / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D011817:Rabbits; D014357:Trypsin
D046911:Macromolecular Substances; D006006:Glycogen Synthase; D010744:Phosphoric Monoester Hydrolases; D006007:Glycogen-Synthase-D Phosphatase; D014357:Trypsin