title: Inhibitory effect of regucalcin on Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity in rat kidney cytosol.
abstract: The effect of regucalcin, a novel Ca2+-binding protein, on Ca2+/calmodulin-dependent cyclic adenosine monophosphate (AMP) phosphodiesterase activity in the cytosol of rat renal cortex was investigated. Regucalcin with physiologic concentration (10[-7] M) in rat kidney had no effect on cyclic AMP phosphodiesterase activity in the absence of CaCl2 and calmodulin. However, the activatory effect of both CaCl2 (10 microM) and calmodulin (20 U/ml) on cyclic AMP phosphodiesterase was markedly inhibited by the addition of regucalcin (10[-8] to 10[-6] M) in the enzyme reaction mixture. The inhibitory effect of regucalcin on the enzyme activity was also seen in the presence of CaCl2 (5-50 microM) or calmodulin (5-50 U/ml) with increasing concentrations. The presence of trifluoperazine (10 microM), an antagonist of calmodulin, caused a partial inhibition of Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity. This inhibition was further enhanced by the addition of regucalcin (10[-7] M). The inhibitory effect of regucalcin (10[-7] M) was not seen in the presence of 20 microM trifluoperazine. Moreover, the activatory effect of calmodulin (20 U/ml) on cyclic AMP phosphodiesterase was not entirely seen, when calmodulin was added 10 min after incubation in the presence of CaCl2 (10 microM) and regucalcin (10[-7] M). The present results demonstrates that regucalcin has an inhibitory effect on Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activation in the cytosol of 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: Yamaguchi
authors.forename: H
authors.initials: H
authors.lastname: Kurota
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D002135:Calcium-Binding Proteins / Q000494:pharmacology*; D002265:Carboxylic Ester Hydrolases; D000242:Cyclic AMP / Q000378:metabolism; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1; D003600:Cytosol / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D047908:Intracellular Signaling Peptides and Proteins; D007672:Kidney Cortex / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D010727:Phosphoric Diester Hydrolases; D051381:Rats; D017208:Rats, Wistar; D015238:Sulfotransferases
chemical_list: D002135:Calcium-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D000242:Cyclic AMP; D015238:Sulfotransferases; C028152:alcohol sulfotransferase; D002265:Carboxylic Ester Hydrolases; C513325:Rgn protein, rat; D010727:Phosphoric Diester Hydrolases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1; D015106:3',5'-Cyclic-GMP Phosphodiesterases