title: Separation and characterization of two phosphorylase phosphatase inhibitors from rabbit skeletal muscle.
abstract: Two heat-stable and trypsin-labile inhibitors of phosphorylase phosphatase, designated inhibitor-1 and inhibitor-2, were partially purified from extracts of rabbit skeletal muscle by heating and coloumn chromatography using DEAE-dellulose and Bio-gel P-60. Inhibitor-1 exists in an active phosphorylated form and an inactive dephosphorylated form. The interconversion of phosphorylated inhibitor-1 and dephosphorylated inhibitor-1 is mediated by protein kinase dependent on adenosine 3':5'-monophosphate (cyclic AMP) and a Mn2+-stimulated phosphoprotein phosphatase. Inhibitory activity of inhibitor-2 is not influenced by treatment with either the kinase or the Mn2+-stimulated phosphatase. The molecular weights of inhibitor-1 and inhibitor-2 estimated by sodium dodecylsulfate-polyacrylamide gel electrophoresis are 26000 and 33000 respectively. Both inhibitor-1 and inhibitor-2 inhibit phosphorylase phosphatase by a mechanism which appears to be non-competitive with respect to the substrate phosphorylase a. Inhibitor fractions at early stages of purification also inhibit cyclic-AMP-dependent histone phosphorylation, but this kinase inhibitory activity resides with a protein moiety which is separable from inhibitor-1 and inhibitor-2.
mesh_terms: D000227:Adenine Nucleotides / Q000494:pharmacology; D000818:Animals; D002848:Chromatography, DEAE-Cellulose; D000242:Cyclic AMP / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology; D008970:Molecular Weight; D009124:Muscle Proteins / Q000302:isolation & purification / Q000502:physiology; D009132:Muscles / Q000201:enzymology*; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors*; D010765:Phosphorylase Phosphatase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D011817:Rabbits
chemical_list: D000227:Adenine Nucleotides; D009124:Muscle Proteins; D008345:Manganese; D000242:Cyclic AMP; D011494:Protein Kinases; D010765:Phosphorylase Phosphatase; D010744:Phosphoric Monoester Hydrolases