香港科技大学２７日发布消息，其生命科学部客座教授张明杰及其团队对动物侦测光的视觉系统研究取得重大突破。该突破对研究视网膜色素变性及其他人类视觉障碍将有很大帮助。

据介绍，每３０００人就有一人患有视网膜色素变性，其早期病症表现为夜盲。此外，科大研究团队的最新成果对于了解人类的癌症、神经退化及免疫力障碍等疾病的生物信号转导过程也有帮助。

科大的消息说，２４日出版的最新一期生命科学界顶级权威杂志《细胞》，选取了这一研究作为封面文章。

据介绍，过去数十年来科学家一直努力研究动物视觉系统的机理，譬如动物如何在黑夜、强烈日光及其他情况下侦测光，及人类眼睛如何于不同的光度环境下作出反应并调控光的接收。大部分动物都有视觉侦测系统，即不同形态的感光细胞，尽管这些感光细胞的设计与目的各有不同，但它们吸收光信号（或光子）转化为视觉反应（或电子反应）的机理却十分相似。

张明杰教授及其研究团队利用果蝇的感光细胞作为模型系统，研究出动物的感光细胞如何以极高的速度侦测强度差距极大的光信号。

张明杰教授表示，人类以及苍蝇等昆虫的视觉系统能够以几十毫秒至几百毫秒的高速在差异很大的环境内侦测光线的存在，如果在这些方面有所缺憾，后果不堪设想。譬如说，如果人类不能在不到一秒的时间内对高速驶来的车辆有所反应，或者苍蝇不能够于一瞬间侦测到迎面而来的苍蝇拍，便会闪避不及。

原文出处：

Cell   DOI：10.1016/j.cell.2011.05.015

The INAD Scaffold Is a Dynamic, Redox-Regulated Modulator of Signaling in the Drosophila Eye

Wei Liu, Wenyu Wen, Zhiyi Wei, Jiang Yu, Fei Ye, Che-Hsiung Liu, Roger C. Hardie, Mingjie Zhang

INAD is a scaffolding protein that regulates signaling in Drosophila photoreceptors. One of its PDZ domains, PDZ5, cycles between reduced and oxidized forms in response to light, but it is unclear how light affects its redox potential. Through biochemical and structural studies, we show that the redox potential of PDZ5 is allosterically regulated by its interaction with another INAD domain, PDZ4. Whereas isolated PDZ5 is stable in the oxidized state, formation of a PDZ45 supramodule locks PDZ5 in the reduced state by raising the redox potential of its Cys606/Cys645 disulfide bond by 330 mV. Acidification, potentially mediated via light and PLCβ-mediated hydrolysis of PIP2, disrupts the interaction between PDZ4 and PDZ5, leading to PDZ5 oxidation and dissociation from the TRP Ca2+ channel, a key component of fly visual signaling. These results show that scaffolding proteins can actively modulate the intrinsic redox potentials of their disulfide bonds to exert regulatory roles in signaling.