Kersting Michael C, Ryals Phillip E
Department of Biochemistry and Molecular Biology, Mississippi State University, Mississippi State, Mississippi 39762, USA.
J Eukaryot Microbiol. 2004 May-Jun;51(3):307-11. doi: 10.1111/j.1550-7408.2004.tb00571.x.
The transport characteristics of (1D)chiro-inositol by the ciliate Tetrahymena were examined in competition studies employing 3Hchiro-inositol. (1D)chiro-Inositol transport was competed by unlabeled (1D)chiro-inositol, myo-inositol, scyllo-inositol, and D-glucose in a concentration-dependent manner. Conversely, (1D)chiro-inositol competed for [3H]myo- and [3H]scyllo-inositol transport. Lineweaver-Burke analysis of the competition data indicated a Km of 10.3 mM and a Bmax of 4.7 nmol/min/mg for (1D)chiro-inositol. Transport of (1D)chiro-inositol was inhibited by cytochalasin B, an inhibitor of facilitated glucose transporters, and phlorizin, an inhibitor of sodium-dependent transporters. Removal of sodium from the radiolabeling buffer also inhibited uptake. The presence of 0.64 mM calcium or magnesium ions exerted negligible effects on transport, although potassium was inhibitory. 3Hchiro-Inositol was shown to be incorporated into Tetrahymena phosphoinositides.
在使用3H手性肌醇的竞争研究中，检测了纤毛虫嗜热四膜虫对(1D)手性肌醇的转运特性。未标记的(1D)手性肌醇、肌醇、 scyllo-肌醇和D-葡萄糖以浓度依赖的方式竞争(1D)手性肌醇的转运。相反，(1D)手性肌醇竞争[3H]肌醇和[3H]scyllo-肌醇的转运。对竞争数据进行Lineweaver-Burke分析表明，(1D)手性肌醇的Km为10.3 mM，Bmax为4.7 nmol/min/mg。促进性葡萄糖转运蛋白抑制剂细胞松弛素B和钠依赖性转运蛋白抑制剂根皮苷抑制了(1D)手性肌醇的转运。从放射性标记缓冲液中去除钠也抑制了摄取。尽管钾具有抑制作用，但0.64 mM钙或镁离子对转运的影响可忽略不计。已证明3H手性肌醇可掺入嗜热四膜虫的磷酸肌醇中。
