Yamaguchi M, Oishi K
Laboratory of Metabolism and Endocrinology, Graduate School of Nutritional Sciences, University of Shizuoka, Japan.
Mol Cell Biochem. 1993 Aug 11;125(1):43-9. doi: 10.1007/BF00926833.
The role of Ca(2+)-stimulated adenosine 5'-triphosphatase (Ca(2+)-ATPase) in Ca2+ sequestering of rat liver nuclei was investigated. Ca(2+)-ATPase activity was calculated by subtracting Mg(2+)-ATPase activity from (Ca(2+)-Mg2+)-ATPase activity. Ca2+ uptake and release were determined with a Ca2+ electrode. Nuclear Ca(2+)-ATPase activity increased linearly in the range of 10-40 microM Ca2+ addition. With those concentrations, Ca2+ was completely taken up by the nuclei dependently on ATP (2 mM). Nuclear Ca(2+)-ATPase activity was decreased significantly by the presence of arachidonic acid (25 and 50 microM), nicotinamide-adenine dinucleotide (NAD+; 2 mM) and zinc sulfate (2.5 and 5.0 microM). These reagents caused a significant decrease in the nuclear Ca2+ uptake and a corresponding elevation in Ca2+ release from the nuclei. Moreover, calmodulin (10 micrograms/ml) increased significantly nuclear Ca(2+)-ATPase activity, and this increase was not seen in the presence of trifluoperazine (10 microM), an antagonist of calmodulin. The present findings suggest that Ca(2+)-ATPase plays a role in Ca2+ sequestering by rat liver nuclei, and that calmodulin is an activator. Moreover, the inhibition of Ca(2+)-ATPase may evoke Ca2+ release from the Ca(2+)-loaded nuclei.
研究了钙离子刺激的腺苷三磷酸酶（Ca(2+)-ATPase）在大鼠肝细胞核钙离子螯合中的作用。通过从（Ca(2+)-Mg2+）-ATPase活性中减去Mg(2+)-ATPase活性来计算Ca(2+)-ATPase活性。用钙离子电极测定钙离子的摄取和释放。在添加10 - 40微摩尔/升钙离子的范围内，细胞核Ca(2+)-ATPase活性呈线性增加。在这些浓度下，钙离子在2毫摩尔/升ATP存在的情况下被细胞核完全摄取。花生四烯酸（25和50微摩尔/升）、烟酰胺腺嘌呤二核苷酸（NAD+；2毫摩尔/升）和硫酸锌（2.
