Activity-Dependent Expression

rAAV-RAM-d2TTA::TRE-hChR2(H134R)-EYFP-WPRE-bGH polyA

Use an optimized activity-dependent promoter to mark active cells; the light-activated element is expressed under physiological conditions in the Tet-off system, but ChR2 is not expressed in the presence of Dox This AAV expresses hChR2(H134R)-EYFP driven by an ubiquitous Ef1α promoter. The 1.2 Kb EF1α promoter is a commonly used, constitutive promoter derived from human elongation factor-1 alpha (EF1α). It is often used in conditions where the other constitutive promoters, such as CMV, have diminished activity or have been silenced. Channelrhodopsins are light-gated ion channels that exist naturally in microalgae. hChR2 is a humanized version of ChR2 for mammalian expression. It is maximally excited by 470 nm light. The wild-type, as well as a few mutations, provide the fastest excitation of the channelrhodopsins offered, and are widely used in optogenetics techniques in neuroscience. Due to delayed channel closure, hChR2(H134R) is a gain-of-function mutation that produces larger photocurrents than wild-type hChR2, but slows down channel kinetics.