Fain G L, Matthews H R, Cornwall M C
Dept of Physiological Science, University of California, Los Angeles 90095, USA.
Trends Neurosci. 1996 Nov;19(11):502-7. doi: 10.1016/S0166-2236(96)10056-4.
Exposure of the eye to bright light bleaches a significant fraction of the photopigment in rods and cones and produces a prolonged decrease in the sensitivity of vision, which recovers slowly as the photopigment is regenerated. This sensitivity decrease is larger than would be expected merely from the decrease in the concentration of the pigment. Recent experiments have shown that the decrease in sensitivity is produced largely by an excitation of the phototransduction cascade by bleached pigment; even in darkness, it produces an equivalent background similar to that produced by real steady background illumination. Thus, excitation produced by a form of rhodopsin thought previously to be inactive has a profound effect on the physiology of the photoreceptor. This raises the possibility that forms of other G protein-coupled receptors thought to be inactive might also play an important role in signal transduction and disease.
眼睛暴露于强光下会使视杆细胞和视锥细胞中的大量光色素褪色，并导致视力敏感度长时间下降，随着光色素的再生，视力敏感度会缓慢恢复。这种敏感度下降比仅由色素浓度降低所预期的要大。最近的实验表明，敏感度下降主要是由漂白色素对视转导级联反应的激发所导致的；即使在黑暗中，它也会产生与真实稳定背景光照所产生的等效背景。因此，一种以前被认为无活性的视紫红质形式所产生的激发对光感受器的生理功能有深远影响。这就增加了一种可能性，即其他被认为无活性的G蛋白偶联受体形式可能在信号转导和疾病中也发挥重要作用。
