Fig. 1.
Combined opto- and chemogenetic control with luminopsins. (a) An optogenetic element (here: channelrhodopsin, ChR) can be activated by a physical light source (LED, laser, arc lamp). (b) The same optogenetic element, when fused to a luciferase (here: Gaussia luciferase, Gluc) by a 15-amino acid linker, can also be activated by “biological” light, which is produced when the attached luciferase catalyzes oxidation of the supplied substrate coelenterazine (CTZ). Fused to the C-terminus of the optogenetic element is the fluorescent reporter YFP, allowing identification of cells expressing the element. The optogenetic element can be a channel or a pump, and depending on its biophysical properties can activate (LMO) or inhibit (iLMO) a neuron