title: Inhibitory effect of regucalcin on Ca2+/calmodulin-dependent phosphatase activity in rat renal cortex cytosol.
abstract: The effect of regucalcin, a Ca2+-binding protein, on Ca2+/calmodulin-dependent phosphatase activity in rat renal cortex cytosol was investigated. The addition of Ca2+/calmodulin in the enzyme reaction mixture caused a significant increase in the dephosphorylation of p-nitrophenylphosphate and phosphotyrosine used as the substrate for phosphatase in rat renal cortex cytosol. The presence of regucalcin (10(-6) M) in the enzyme reaction mixture caused a complete inhibition of Ca2+/calmodulin-dependent phosphatase activity in renal cortex cytosol. A half maximum effect of regucalcin inhibition was seen at 10(-8) M concentration. Moreover, phosphatase activity of purified calcineurin was significantly enhanced by the addition of Ca2+/calmodulin. This enhancement was completely inhibited by the presence of regucalcin (10(-7) M). The inhibitory effect of regucalcin was not weakened by increasing concentrations of CaCl2 (10(-6) to 10(-4) M). The present results suggest that regucalcin can inhibit Ca2+/calmodulin-dependent phosphatase activity in rat renal cortex.
authors.affiliation: Laboratory of Endocrinology and Molecular Metabolism, Graduate School of Nutritional Sciences, University of Shizuoka, Shizuoka City, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Omura
authors.forename: H
authors.initials: H
authors.lastname: Kurota
authors.forename: M
authors.initials: M
authors.lastname: Yamaguchi
mesh_terms: D000818:Animals; D019703:Calcineurin / Q000378:metabolism; D002122:Calcium Chloride / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000494:pharmacology*; D002265:Carboxylic Ester Hydrolases; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins; D007672:Kidney Cortex / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D015238:Sulfotransferases
chemical_list: D002135:Calcium-Binding Proteins; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D015238:Sulfotransferases; C028152:alcohol sulfotransferase; D002265:Carboxylic Ester Hydrolases; C513325:Rgn protein, rat; C110531:calmodulin dependent protein kinase II phosphatase; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D002122:Calcium Chloride