Inhibitory effect of calcium-binding protein regucalcin on Ca2+/calmodulin-dependent cyclic nucleotide phosphodiesterase activity in rat liver cytosol
- 1 July 1991
- journal article
- Published by Springer Nature in Molecular and Cellular Biochemistry
- Vol. 106 (1)
- https://doi.org/10.1007/bf00231185
Abstract
The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on Ca2+/calmodulin-dependent cyclic nucleotide (AMP) phosphodiesterase activity in rat liver cytosol was investigated. The addition of Ca2+ (50 µM) and calmodulin 160 U/ml in the enzyme reaction mixture caused a significant increase in cyclic AMP phosphodiesterase activity. This increase was inhibited by the presence of regucalcin (0.5-3.0 µM); the inhibitory effect was complete at 1.0 µM. Regucalcin (1.0 µM) did not have an appreciable effect on basal activity without Ca2+ and calmodulin. The inhibitory effect of regucalcin was still evident even at several fold higher concentrations of calmodulin (160–480 U/ml). However, regucalcin (1.0 µM) did not inhibit Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity in the presence of 100 and 200 µM Ca2+ added. Meanwhile, Cd2 (25–100 µM)-induced decrease in Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity was not reversed by the presence of regucalcin (1.0 µM). The present results suggest that regucalcin can regulate Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity due to binding Ca2+ in liver cells.Keywords
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