Suppressive Effect of Endogenous Regucalcin of Guanosine Triphosphatase Activity in Rat Liver Nucleus

概要

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The effect of regucalcin, a regulatory protein of Ca^<2+> signaling, on guanosine triphosphatase(GTPase)activity in the nuclei of rat liver was investigated. GTPase activity was significantly increased by the addition of CaCl_2(50μ_M)in the enzyme reaction mixture. This increase was not seen in the presence of trifluoperazine(25μ_M), an antagonist of calmodulin, which could decrease nuclear GTPase activity, suggesting that nuclear endogenous calmodulin is involved in an increase in the enzyme activity related to Ca^<2+> addition. The presence of regucalcin(0.5μ_M)in the enzyme reaction mixture caused a significant decrease in nuclear GTPase activity. The enzyme activity was significantly raised in the presence of anti-regucalcin monoclonal antibody(25 and 50ng/ml)in the reaction mixture. This increase was completely abolished by the addition of regucalcin(0.5μ_M). Also, the effect of regucalcin addition in increasing nuclear GTPase activity was seen in the presence of EGTA(0.1μ_M), a chelator of Ca^<2+>. The present study demonstrates that endogenous regucalcin has a suppressive effect on GTPase activity in the nuclei of rat liver.
公益社団法人日本薬学会の論文
2001-08-01