Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0647, USA.
Exp Physiol. 2011 Jan;96(1):19-25. doi: 10.1113/expphysiol.2009.051961. Epub 2010 Jul 9.
Channelrhodopsins (ChRs) are light-activated channels from algae that provide these organisms with fast sensors to visible light for phototaxis. Since its discovery, channelrhodopsin-2 (ChR2) has been used as a research tool to depolarize membranes of excitable cells with light. Subsequent chimeragenesis, mutagenesis and bioinformatic approaches have introduced additional ChR variants, such as channelrhodopsin-2 with H134R mutation (ChR2/H134R), channelrhodopsin-2 with E123T mutation (ChETA), Volvox carteri channelrhodopsin-1 (VChR1), Volvox carteri channelrhodopsin-2 (VChR2), channelrhodopsin-2 with C128 or D156A mutations (ChR2/C128X/D156A), chimera D (ChD), chimera EF (ChEF) and chimera EF with I170V mutation (I170V). Each of these ChR variuants has unique features and limitations, but there are few resources summarizing and comparing these ChRs in a systematic manner. In this review, the seven following key properties of ChRs that have significant influences on their effectiveness as research tools are examined: conductance, selectivity, kinetics, desensitization, light sensitivity, spectral response and membrane trafficking. Using this information, valuable qualities and deficits of each ChR variant are summarized. Optimal uses and potential future improvements of ChRs as optogenetic tools are also discussed.
通道视紫红质（ChR）是来自藻类的光激活通道，为这些生物提供了快速感知可见光的传感器，用于趋光性。自发现以来，通道视紫红质-2（ChR2）已被用作研究工具，通过光使可兴奋细胞的膜去极化。随后的嵌合、突变和生物信息学方法引入了其他 ChR 变体，例如具有 H134R 突变的通道视紫红质-2（ChR2/H134R）、具有 E123T 突变的通道视紫红质-2（ChETA）、衣藻通道视紫红质-1（VChR1）、衣藻通道视紫红质-2（VChR2）、具有 C128 或 D156A 突变的通道视紫红质-2（ChR2/C128X/D156A）、嵌合体 D（ChD）、嵌合体 EF（ChEF）和具有 I170V 突变的嵌合体 EF（I170V）。这些 ChR 变体中的每一种都具有独特的特征和局限性，但很少有资源以系统的方式总结和比较这些 ChR。在这篇综述中，检查了对其作为研究工具的有效性有重大影响的七种以下 ChR 的关键特性：电导率、选择性、动力学、脱敏、光敏感性、光谱响应和膜转运。利用这些信息，总结了每种 ChR 变体的宝贵品质和缺陷。还讨论了 ChR 作为光遗传学工具的最佳用途和潜在的未来改进。
