Transducin GTPase provides for rapid quenching of the cGMP cascade in rod outer segments

FEBS Letters

Lukjanov, K.A.¹  Arshavsky, V.Yu.¹  Antoch, M.P.¹  Philippov, P.P.¹ 

[1]A.N. Belozersky Laboratory of Molecular Biology and Bioorganic Chemistry, Moscow State University, Moscow 119899, USSR

关键词: Photoreception;    Phosphodiesterase;    Transducin GTPase;    Signal quenching;    ROS;    rod outer segments;    T;    transducin;    PDE;    cyclic GMP phosphodiesterase;    Mops;    morpholinepropane-sulfonic acid;    AppNHp;    adenylyl imidodiphosphate;   

DOI  :  10.1016/0014-5793(89)80754-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The role of transducin GTPase in rapid cGMP phosphodiesterase quenching was studied by simultaneous registration of GTP hydrolysis and phosphodiesterase activity in the same rod outer segments (ROS) preparation. The results thus obtained allow the conclusion that: (i) phosphodiesterase quenching coincides with transducin-bound GTP hydrolysis independently of ROS concentration; (ii) an increase in the ROS concentration results in the acceleration of cascade quenching due to the existence of a GTPase accelerating mechanism in ROS; (iii) approximation to physiological conditions (protein concentration, temperature) provides a transducin GTPase rate equal to 1–2 turnovers per second i.e., sufficiently high for satisfying the real rate of photoresponse reversion in dark-adapted rods.

【 授权许可】

Unknown