Cambridge University, Department of Physiology Development and Neuroscience, Downing St CB2 3EG, United Kingdom.
The University of Sheffield, Department of Biomedical Science, Sheffield S10 2TN, United Kingdom; Beijing Normal University, National Key laboratory of Cognitive Neuroscience and Learning, China.
Curr Opin Neurobiol. 2015 Oct;34:37-45. doi: 10.1016/j.conb.2015.01.008. Epub 2015 Jan 29.
Phototransduction in Drosophila's microvillar photoreceptors is mediated by phospholipase C (PLC) resulting in activation of two distinct Ca(2+)-permeable channels, TRP and TRPL. Here we review recent evidence on the unresolved mechanism of their activation, including the hypothesis that the channels are mechanically activated by physical effects of PIP2 depletion on the membrane, in combination with protons released by PLC. We also review molecularly explicit models indicating how Ca(2+)-dependent positive and negative feedback along with the ultracompartmentalization provided by the microvillar design can account for the ability of fly photoreceptors to respond to single photons 10-100× more rapidly than vertebrate rods, yet still signal under full sunlight.
果蝇微绒毛光感受器中的光转导由磷脂酶 C (PLC)介导，导致两种不同的 Ca(2+)通透性通道 TRP 和 TRPL 的激活。在这里，我们回顾了关于它们激活的未解决机制的最新证据，包括通道被 PIP2 耗竭对膜的物理效应以及 PLC 释放的质子机械激活的假说。我们还回顾了分子明确的模型，这些模型表明 Ca(2+)依赖性正反馈和负反馈以及微绒毛设计提供的超高分隔度如何使果蝇光感受器能够对单个光子的响应速度比脊椎动物的视杆快 10-100 倍，而在全日光下仍能发出信号。
