title: Rabbit kidney cortex phosphorylase phosphatases: evidence for complexes between high molecular weight forms and heat-stable inhibitor proteins.
abstract: Two forms of high molecular weight phosphorylase phosphatase have been partially resolved by gel filtration chromatography of rabbit kidney cortex extracts. Two heat-stable inhibitor proteins co-eluted with the phosphatase peaks. Phosphorylase phosphatase and heat-stable inhibitor activity also co-migrated on gel electrophoresis of cortex extracts. When extracts were heated to 95 degrees for 5 minutes prior to gel filtration or electrophoresis, phosphorylase phosphatase inhibitor activity eluted at a lower molecular weight and a higher mobility, respectively. Storing cortex extracts at -20 degrees for 6 months resulted in partial conversion of both phosphatase and inhibitor activities to lower molecular weight forms which co-eluted on gel filtration. The two inhibitor peaks from gel filtration chromatography were heat-treated and characterized. Both inhibitor peaks had molecular weight of 25,000 to 35,000. The inhibitory activity of one of the peaks was increased about 3.5-fold by incubation with cyclic AMP-dependent protein kinase and ATP, and required higher concentrations of TCA to be precipitated. Hence, one of the inhibitor peaks resembled rabbit muscle inhibitor -1, while the other peak may represent an inhibitor similar to rabbit muscle inhibitor -2. These results represent the first indication that low molecular weight heat-stable inhibitor proteins may be bound to high molecular weight phosphorylase phosphatases in the cell.
mesh_terms: D000818:Animals; D002850:Chromatography, Gel; D004355:Drug Stability; D004789:Enzyme Activation; D007672:Kidney Cortex / Q000201:enzymology*; D007700:Kinetics; D008970:Molecular Weight; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010765:Phosphorylase Phosphatase / Q000302:isolation & purification / Q000378:metabolism*; D011494:Protein Kinases / Q000494:pharmacology; D011817:Rabbits; D014357:Trypsin / Q000494:pharmacology
chemical_list: D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases; D010765:Phosphorylase Phosphatase; D014357:Trypsin