a Department of Medical Neurobiology , Faculty of Medicine and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University , Jerusalem , Israel.
b Department of Biosensorics , Institute of Physiology, University of Hohenheim , Stuttgart , Germany.
Channels (Austin). 2017 Nov 2;11(6):678-685. doi: 10.1080/19336950.2017.1361073. Epub 2017 Aug 18.
Drosophila photoreceptors respond to oscillating light of high frequency (∼100 Hz), while increasing the oscillating light intensity raises the maximally detected frequency. Recently, we reported that dephosphorylation of the light-activated TRP ion channel at S936 is a fast, graded, light-, and Ca-dependent process. We further found that this process affects the detection limit of high frequency oscillating light. Accordingly, transgenic Drosophila, which do not undergo phosphorylation at the S936-TRP site (trp), revealed a short time-interval before following the high stimulus frequency (oscillation-lock response) in both dark- and light-adapted flies. In contrast, the trp transgenic flies, which mimic constant phosphorylation, showed a long-time interval to oscillation-lock response in both dark- and light-adapted flies. Here we extend these findings by showing that dark-adapted trp flies reveal light-induced current (LIC) with short latency relative to trp or trp flies, indicating that the channels are a limiting factor of response kinetics. The results indicate that properties of the light-activated channels together with the dynamic light-dependent process of TRP phosphorylation at the S936 site determine response kinetics.
果蝇感光器对高频（约 100 Hz）的振荡光作出反应，而增加振荡光强度会提高最大检测频率。最近，我们报告称，TRP 离子通道在 S936 处的去磷酸化是一个快速、分级、光依赖和 Ca 依赖的过程。我们进一步发现，这个过程影响高频振荡光的检测极限。因此，不会在 S936-TRP 位点（trp）处发生磷酸化的转基因果蝇在黑暗和适应光条件下都表现出紧随高频刺激后的短时间间隔（振荡锁定反应）。相比之下，模拟持续磷酸化的 trp 转基因果蝇在黑暗和适应光条件下均表现出长的时间间隔以响应振荡锁定。在这里，我们通过显示暗适应的 trp 果蝇相对于 trp 或 trp 果蝇具有较短潜伏期的光诱导电流（LIC）来扩展这些发现，表明通道是响应动力学的限制因素。结果表明，光激活通道的特性以及 S936 位点处 TRP 磷酸化的动态光依赖性过程决定了响应动力学。
