Lanini L, Bachs O, Carafoli E
Institute of Biochemistry, Swiss Federal Institute of Technology (ETH), Zurich.
J Biol Chem. 1992 Jun 5;267(16):11548-52.
The envelope membrane of rat liver nuclei contains a P-type Ca(2+)-transporting pump, revealed by the presence of a Ca(2+)-stimulated phosphoenzyme. The level of the nuclear phosphoenzyme in autoradiographed polyacrylamide gels was decreased by lanthanum, as typically observed in the endoplasmic reticulum Ca2+ pump. It was also decreased by thapsigargin and 2,5-di-(tert-butyl)-1,4-benzohydroquinone, two accepted inhibitors of the endoplasmic reticulum Ca(2+)-ATPase. Comparative proteolysis of the phosphorylated enzyme of liver microsomes (endoplasmic reticulum) and nuclear membranes revealed an identical cleavage pattern. In addition, antibodies raised against the endoplasmic reticulum Ca2+ pump cross-reacted with the pump in the nuclear membranes. The findings show that nuclear membranes contain a Ca(2+)-transporting pump closely related to that of the endoplasmic reticulum, if not identical to it. The pump is likely to be involved in the control of nuclear free calcium.
大鼠肝细胞核的包膜含有一种P型Ca(2+)转运泵，这可通过Ca(2+)刺激的磷酸化酶的存在得以揭示。自显影聚丙烯酰胺凝胶中核磷酸化酶的水平会被镧降低，这是内质网Ca2+泵中通常观察到的情况。它也会被毒胡萝卜素和2,5-二（叔丁基）-1,4-苯二酚降低，这两种物质是内质网Ca(2+)-ATP酶公认的抑制剂。对肝微粒体（内质网）和核膜的磷酸化酶进行比较性蛋白水解，发现其裂解模式相同。此外，针对内质网Ca2+泵产生的抗体与核膜中的泵发生交叉反应。这些发现表明，核膜含有一种与内质网Ca(2+)转运泵密切相关（即便不完全相同）的Ca(2+)转运泵。该泵可能参与核游离钙的调控。
