Sub‐second turnover of transducin GTPase in bovine rod outer segments A light scattering study

FEBS Letters

Wagner, Rafael¹  Uhl, Rainer¹  Ryba, Nicholas¹ 

[1] Max-Planck-Institut für Biophysikalische Chemie, Am Faßberg, D-3400 Göttingen, FRG

关键词: Photoreception;    Transducin deactivation;    GTPase turnover;    Light scattering;   

DOI  :  10.1016/0014-5793(88)81299-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A fast, regenerative light scattering signal from bovine ROS, the P_A-signal, reflects the light-induced, transient activation of transducin. Its rate of recovery depends on the number of photolysed rhodopsin molecules, indicating that rhodopsin deactivation and not GTPase activity is rate limiting in our in vitro system. When rhodopsin deactivation is accelerated (in the presence of NH₂OH), P_A-signal recovery is also accelerated. A GTPase turnover number of more than 2 s⁻¹ (at 37°C) can be derived from these experiments. This is more than one order of magnitude faster than the GTPase rates so far described in the literature and is rapid enough for a physiological shut-off mechanism. The fast GTPase is attributed to a highly intact disk stack, which never releases transducin into the free aqueous space.

【 授权许可】

Unknown