Structural insights into ion conduction by channelrhodopsin 2

The inner workings of an optogenetic tool Channelrhodopsins are membrane channel proteins whose gating is controlled by light. In their native setting, they allow green algae to move in response to light. Their expression in neurons allows precise control of neural activity, an approach known as optogenetics. Volkov et al. describe the high-resolution structure of channelrhodopsin 2, the most widely used optogenetics tool, as well as the structure of a mutant with a longer open-state lifetime (see the Perspective by Gerwert). Light activation perturbs an intricate hydrogen-bonding network to open the channel. The structures provide a basis for designing better optogenetic tools. Science , this issue p. 10.1126/science.eaan8862 ; see also p. 1000