title: Thiophosphate-activated phosphorylase kinase as a probe in the regulation of phosphorylase phosphatase.
abstract: Rabbit muscle nonactivated phosphorylase kinase (EC 2.7.1.38) is converted to thiophosphate-activated phosphorylase kinase by cyclic AMP dependent protein kinase, Mg2+ and ATP-gamma-S/adenosine-5'-O-(s-thiotriphosphate)/. The formation of thiophosphate-activated phosphorylase kinase wal also observed in the protein-glycogen complex from skeletal muscle. This new form of kinase is resistant to the action of phosphatase and behaves as a competitive inhibitor in the dephosphorylation of phosphorylase alpha by phosphorylase phosphatase (Ki = 0.04 mg per ml). The fact that the inhibitory effect of thiophosphate-activated phosphorylase kinase is 3 times higher than in the case of nonactivated kinase, may explain the transient inhibition of phosphorylase phosphatase in the protein-glycogen complex. The use of activated (phosphorylated) phosphorylase kinase supports this assumption since it causes a delay in the dephosphorylation of phosphorylase alpha, i.e. the conversion of phosphorylase alpha into beta could start only after the dephosphorylation of activated phosphorylase kinase.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology; D006003:Glycogen; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009132:Muscles / Q000201:enzymology; D063086:Organothiophosphates / Q000494:pharmacology*; D009946:Organothiophosphorus Compounds / Q000494:pharmacology*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010764:Phosphorylase Kinase / Q000378:metabolism*; D010765:Phosphorylase Phosphatase / Q000378:metabolism*; D006005:Phosphorylases / Q000378:metabolism; D011485:Protein Binding; D011817:Rabbits
chemical_list: D063086:Organothiophosphates; D009946:Organothiophosphorus Compounds; D000255:Adenosine Triphosphate; D006003:Glycogen; D000242:Cyclic AMP; D006005:Phosphorylases; D010764:Phosphorylase Kinase; D010765:Phosphorylase Phosphatase; D010744:Phosphoric Monoester Hydrolases; D008274:Magnesium; D002118:Calcium