Isolation of an active form of the ATP + Mg2+-dependent protein phosphatase stimulated by the deinhibitor protein and by p-nitrophenyl phosphate.
A 75 kDa + 37 kDa-subunit high-Mr form of the ATP + Mg2+-dependent phosphatase, containing no modulator or inhibitor-1 and specific towards the beta-subunit of phosphorylase kinase, was isolated from dog liver. The phosphorylase phosphatase activity is stimulated by the deinhibitor protein, by p-nitrophenyl phosphate or by trypsin treatment. The sensitivity to modulator or inhibitor-1 can be increased dramatically by partial proteolysis. The enzyme inactivation by modulator after trypsin treatment can be reversed by protein kinase FA. The effects of p-nitrophenyl phosphate and the deinhibitor protein are synergistic, and p-nitrophenyl phosphate does not influence the sensitivity of the phosphatase to the heat-stable inhibitor proteins. These observations confirm that p-nitrophenyl phosphate stimulation is a suitable criterion for the identification of the active enzyme forms of the ATP + Mg2+-dependent phosphatase.
Goris
J
J
Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit te Leuven, Campus Gasthuisberg, Belgium.
Merlevede
W
W
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004285:Dogs; D004357:Drug Synergism; D004790:Enzyme Induction / Q000187:drug effects; D007527:Isoenzymes / Q000096:biosynthesis*; D008099:Liver / Q000201:enzymology; D008274:Magnesium / Q000494:pharmacology; D009596:Nitrophenols / Q000494:pharmacology*; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000302:isolation & purification; D011506:Proteins / Q000494:pharmacology*; D014357:Trypsin / Q000494:pharmacology
D007527:Isoenzymes; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D011506:Proteins; C033035:deinhibitor protein, Canis familiaris; C008644:nitrophenylphosphate; D000255:Adenosine Triphosphate; D010749:Phosphoprotein Phosphatases; D014357:Trypsin; D008274:Magnesium