A manganese-dependent protein kinase in gastric gland cytosol.
A protein kinase activity completely dependent on Mn2+ was studied in the cytosolic fraction from rabbit-isolated gastric glands. The manganese-dependent protein kinase (MNPK) activity phosphorylated major 33 kd (pp33) and minor 140 kd (pp140) endogenous proteins. The MNPK activity displayed a Kact for Mn2+ of 7.5 mmol/L. MNPK showed no preference for adenosine triphosphate or guanosine triphosphate with a Kact of 10 mumol/L for both. The kinase was differentiated from other known kinases since calmodulin, cyclic adenosine monophosphate, and phospholipids failed to stimulate pp33 phosphorylation. Furthermore, the protein kinase inhibitors trifluoperazine, the Walsh inhibitor protein, and heparin, as well as the phosphatase inhibitor p-nitrophenylphosphate failed to alter MNPK activity. The results indicate that novel MNPK activity is present in gastric gland cytosol. Elucidation of intracellular protein kinase activities may provide insights into the regulation of gastric secretory process.
D000818:Animals; D001345:Autoradiography; D003600:Cytosol / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005753:Gastric Mucosa / Q000201:enzymology*; D006493:Heparin / Q000494:pharmacology; D008345:Manganese / Q000378:metabolism*; D009596:Nitrophenols / Q000494:pharmacology; D009943:Organophosphorus Compounds / Q000494:pharmacology; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000302:isolation & purification* / Q000378:metabolism; D011817:Rabbits; D014268:Trifluoperazine / Q000494:pharmacology
D009596:Nitrophenols; D009943:Organophosphorus Compounds; D047428:Protein Kinase Inhibitors; D014268:Trifluoperazine; C008644:nitrophenylphosphate; D008345:Manganese; D006493:Heparin; D011494:Protein Kinases