Cosentino, C. et al. Science 348, 707–710 (2015).

Optogenetic approaches to activate neurons are widely used in neuroscience, but inhibitory tools are less well established. Cosentino et al. engineered a blue light–induced K+ channel by fusing the viral K+ channel Kcv with the LOV2-Ja light switch and optimizing the dynamic range and expression level of the engineered protein. The resulting channel, named BLINK1, is selective for potassium ions and is highly conductive. Its slow activation and deactivation kinetics make the channel an ideal tool for applications that require neural inactivation over long periods of time. The researchers demonstrated the in vivo suitability of BLINK1 in zebrafish. Under blue light illumination, fewer larvae showed an escape response after touch if injected with mRNA encoding BLINK1, behavior consistent with the inhibitory role of BLINK1.