Fukada Y, Yoshizawa T, Saito T, Ohguro H, Akino T
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
FEBS Lett. 1990 Feb 26;261(2):419-22. doi: 10.1016/0014-5793(90)80606-j.
In the presence of a photobleaching intermediate of unphosphorylated or phosphorylated rhodopsin (Rh*), the binding of GppNHp to transducin was measured with or without arrestin for elucidation of the shut-off mechanism of the visual transduction process in bovine rod outer segments. The ability of Rh* to catalyze the formation of the transducin-GppNHp complex in the absence of arrestin was independent of the degree of phosphorylation of Rh*. Furthermore, the catalyzing ability of the phosphorylated Rh* was not reduced by the addition of arrestin. These observations indicate that the interaction between phosphorylated Rh* and transducin was not inhibited by arrestin. Thus, the hypothesis was not supported that the PDE shut-off process is a simple competition between transducin and arrestin for binding to phosphorylated Rh*.
在未磷酸化或磷酸化视紫红质（Rh*）的光漂白中间体存在的情况下，在有或没有抑制蛋白的条件下测量GppNHp与转导蛋白的结合，以阐明牛视杆外段视觉转导过程的关闭机制。在没有抑制蛋白的情况下，Rh催化转导蛋白-GppNHp复合物形成的能力与Rh的磷酸化程度无关。此外，添加抑制蛋白不会降低磷酸化Rh的催化能力。这些观察结果表明，磷酸化Rh与转导蛋白之间的相互作用不会被抑制蛋白抑制。因此，磷酸二酯酶（PDE）关闭过程是转导蛋白和抑制蛋白之间简单的竞争以结合磷酸化Rh*这一假设未得到支持。
