Shih C K, Wagner R, Feinstein S, Kanik-Ennulat C, Neff N
Graduate Program in Molecular Biology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
Mol Cell Biol. 1988 Aug;8(8):3094-103. doi: 10.1128/mcb.8.8.3094-3103.1988.
The antipsychotic drug trifluoperazine has been long considered a calmodulin inhibitor from in vitro studies but may function in vivo as a more general inhibitor by disturbing ion fluxes and altering the membrane potential. Resistance to trifluoperazine can arise in Saccharomyces cerevisiae cells by alterations in at least three distinct genetic loci. One locus, defined by a spontaneous dominant trifluoperazine resistance mutation (TFP1-408), was isolated and sequenced. The sequence of the TFP1-408 gene revealed a large open reading frame coding for a large protein of 1,031 amino acids with predicted hydrophobic transmembrane domains. A search of existing amino acid sequences revealed a significant homology with F0F1 ATP synthase. Mutant TFP1-408 cells did not grow efficiently in the presence of 50 mM CaCl2, whereas wild-type cells did. Wild-type cells became resistant to trifluoperazine in the presence of 50 mM CaCl2 or 50 mM MgCl2. Mutant cells showed a higher rate of calcium transport relative to wild-type cells. These data suggest that the TFP1 gene product codes for a transmembrane ATPase-like enzyme possibly involved in Ca2+ transport or in generating a transmembrane ion gradient between two cellular compartments.
抗精神病药物三氟拉嗪长期以来在体外研究中被认为是一种钙调蛋白抑制剂，但在体内可能通过干扰离子通量和改变膜电位发挥更广泛的抑制作用。酿酒酵母细胞中至少通过三个不同基因位点的改变可产生对三氟拉嗪的抗性。分离并测序了一个由自发显性三氟拉嗪抗性突变（TFP1-408）定义的基因位点。TFP1-408基因序列显示有一个大的开放阅读框，编码一个含1031个氨基酸的大蛋白，具有预测的疏水跨膜结构域。对现有氨基酸序列的搜索发现与F0F1 ATP合酶有显著同源性。在50 mM氯化钙存在的情况下，突变型TFP1-408细胞生长效率不高，而野生型细胞则可以。在50 mM氯化钙或50 mM氯化镁存在的情况下，野生型细胞对三氟拉嗪产生抗性。相对于野生型细胞，突变型细胞显示出更高的钙转运速率。这些数据表明，TFP1基因产物编码一种类似跨膜ATP酶的酶，可能参与钙离子运输或在两个细胞区室之间产生跨膜离子梯度。
