Regulatory role of ca^<2+> -binging protein requcalcin in signal transduction system and its mechanism

研究Ca^<2+> -结合蛋白requcalcin在肝细胞信号转导系统中的调节作用，得到以下结果：1) Requcalcin直接激活(Ca^<2+>-Mg^<2+>)- atp酶，该激活不参与Ca^<2+>依赖性酶磷酸化。2)常钙素对(Ca^<2+>-Mg^<2+>)- atp酶的激活机制不参与调节受体介导的大鼠肝质膜激素效应的gtp结合蛋白。3) Regucalcin刺激Ca^<2+>从肝核释放，且不受钙调素拮抗剂的影响，提示Regucalcin可调节大鼠肝核Ca^2转运系统。4)花生四烯酸抑制大鼠肝核Ca^<2+>摄取，刺激Ca^<2+>释放。5) NAD^+对细胞核Ca^<2+>摄取有抑制作用。6)肝核为Ca^<2+> - atp酶，可吸收Ca^<2+>。花生四烯酸和NAD^+对酶活性有抑制作用，而芦黄素对酶活性无影响。

The requlatory role of Ca^<2+> -binding protein requcalcin in signal trasnduction system of liver cells was investigated, and the following results were obtained.1) Requcalcin activates directly (Ca^<2+>-Mg^<2+>)-ATPase in liver plasma membranes, an the activation is not involved in the Ca^<2+>-dependent phosphorylation of the enzyme.2) The activating mechanism of requcalcin on (Ca^<2+>-Mg^<2+>)-ATPase is not involved on GTP-binding protein which modulates the receptor-mediated hormonal effect in rat liver plasma menbranes.3) Regucalcin stimulates Ca^<2+> release from liver nuclei, and the effect is not influenced by calmodulin antagonist, suggesting that regucalcin can regulate the Ca^2 transport system in rat liver nuclei.4) Arachidonic acid inhibited Ca^<2+> uptake and stimulated Ca^<2+> release in rat liver nuclei.5) NAD^+ has an inhibitory effect on nuclear Ca^<2+> uptake.6) Liver nuclei were Ca^<2+> -ATPase which can taken up Ca^<2+>.Rgucalcin had no effect on the enzyme activity, although arachidonic acid and NAD^+ inhibited the enzyme activity.