Calcium regulates the rate of rhodopsin disactivation and the primary amplification step in visual transduction

FEBS Letters

Wagner, Rafael²  Uhl, Rainer²  Ryba, Nicholas¹ 

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

关键词: Photoreception;    Transducin disactivation;    Rhodopsin;    Phosphorylation;    Adaptation;    Ca2+;    Light scattering;   

DOI  :  10.1016/0014-5793(89)80479-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The kinetics of the light-induced activation of transducin as well as the subsequent disactivation process can be monitored by means of a specific light scattering transient P_A. In this communication it is demonstrated that the rate of transducin disactivation is calcium dependent, increasing when the calcium concentration is decreased. As a consequence of the accelerated recovery in low calcium, the time to the peak of the transducin activation process is shortened and the gain of the primary amplification step, i.e. the number of transducin molecules activated per bleached rhodopsin, is reduced. Experiments using hydroxylamine as an artificial quencher of rhodopsin activity suggest that calcium acts upon rhodopsin kinase and not upon the rate of the GTPase. This would indicate that calcium may control visual adaptation not only by regulating guanine cyclase activity, but also by affecting the primary step in the transduction cascade, the rhodopsin-transducin coupling

【 授权许可】

Unknown