Hepatic calcium-binding protein regucalcin decreases Ca2+/calmodulin-dependent protein kinase activity in rat liver cytosol.
The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on cytosolic Ca2+/calmodulin-dependent protein kinase activity was investigated. The increase in cytosolic Ca2+/calmodulin-dependent protein kinase activity with passage of incubation time was clearly prevented by the presence of regucalcin (1.0 microM). An appreciable effect of regucalcin was seen at 0.5 microM. The cytosolic Ca2+/calmodulin-dependent protein kinase activity was fairly increased by increasing concentrations of added Ca2+ (0.25-1.0 mM). This increase was clearly blocked by the presence of regucalcin (1.0 microM). The inhibitory effect of regucalcin on the protein kinase activity was also seen with varying concentrations of calmodulin (2.5-15 micrograms). In the presence of regucalcin (1.0 microM), trifluoperazine (50 microM), an antagonist of calmodulin, significantly decreased the cytosolic Ca2+/calmodulin-dependent protein kinase activity. These results suggest that regucalcin can regulate the Ca2(+)-calmodulin effect in liver cytosol.
Mori
S
S
Department of Environmental Biochemistry and Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, Japan.
Yamaguchi
M
M
D000818:Animals; D002135:Calcium-Binding Proteins / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002265:Carboxylic Ester Hydrolases; D003600:Cytosol / Q000201:enzymology*; D047908:Intracellular Signaling Peptides and Proteins; D008099:Liver / Q000201:enzymology*; D008297:Male; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D015238:Sulfotransferases
D002135:Calcium-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D015238:Sulfotransferases; C028152:alcohol sulfotransferase; D002265:Carboxylic Ester Hydrolases; C513325:Rgn protein, rat