Nicotera P, McConkey D J, Jones D P, Orrenius S
Department of Toxicology, Karolinska Institutet, Stockholm, Sweden.
Proc Natl Acad Sci U S A. 1989 Jan;86(2):453-7. doi: 10.1073/pnas.86.2.453.
Addition of ATP to a highly purified fraction of rat liver nuclei incubated with submicromolar concentrations of Ca2+ and trace amounts of 45Ca2+ resulted in the rapid accumulation of 45Ca2+ in the nuclei. This was associated with an increase in intranuclear free Ca2+ concentration as measured with the fluorescent dye 1-[2-(5-carboxyoxazol-2-yl)-6-aminobenzofuran-5-oxy]-2-(2'-a mino-5'- methylphenoxy)ethane-N,N,N',N'-tetraacetic acid (fura-2). Inhibitors of microsomal and mitochondrial Ca2+ translocases had no effect on nuclear Ca2+ sequestration, indicating that it was distinct from previously known intracellular Ca2+-transporting systems. Ca2+ uptake and the associated increase in intranuclear free Ca2+ concentration were prevented by calmidazolium, a potent calmodulin antagonist. Partial characterization of the ATP-stimulated nuclear Ca2+ uptake showed that maximal rates of Ca2+ uptake and increase in intranuclear free Ca2+ level occurred at concentrations of Ca2+ normally present in the cytosol of mammalian cells. Together, these results show that a distinct, ATP- and calmodulin-dependent Ca2+ uptake system exists in liver nuclei. This system may play an important role in the regulation of intranuclear Ca2+-dependent processes.
将ATP添加到用亚微摩尔浓度的Ca2+和痕量45Ca2+孵育的高度纯化的大鼠肝细胞核组分中，导致45Ca2+在细胞核中快速积累。这与用荧光染料1-[2-(5-羧基恶唑-2-基)-6-氨基苯并呋喃-5-氧基]-2-(2'-氨基-5'-甲基苯氧基)乙烷-N,N,N',N'-四乙酸（fura-2）测量的核内游离Ca2+浓度增加有关。微粒体和线粒体Ca2+转运酶的抑制剂对核Ca2+螯合没有影响，表明它与先前已知的细胞内Ca2+运输系统不同。钙调蛋白拮抗剂 calmidazolium可阻止Ca2+摄取以及核内游离Ca2+浓度的相关增加。对ATP刺激的核Ca2+摄取的部分表征表明，Ca2+摄取的最大速率和核内游离Ca2+水平的增加发生在哺乳动物细胞胞质溶胶中正常存在的Ca2+浓度下。这些结果共同表明，肝细胞核中存在一种独特的、依赖ATP和钙调蛋白的Ca2+摄取系统。该系统可能在核内Ca2+依赖性过程的调节中起重要作用。
