BLINK2 (Blue Light Induced K+ channel) is an engineered light-gated K+ channel that was successfully employed for optogenetic inhibition of pain in a rat model (Alberio et al., 2018). Still, BLINK2 shows suboptimal surface expression in mammalian cells that limits its applications. When transiently expressed in HEK 293 cells together with GFP, we find a measurable blue-light activated current in 28-30% only of the GFP-positive cells. To this end, we designed a high throughput screening system which is based on random mutagenesis followed by Fluorescence Associated Cell Sorting (FACS). BLINK2 was engineered to expose an extracellular HA tag for antibody recognition. After preliminary test to analyze the sensitivity of the FACS to BLINK2-HA expression, we create a random library of BLINK2-HA that was transiently expressed in HEK 293 cells. Trough FACS analysis, we sorted the cells expressing variants of BLINK2-HA with a visible membrane expression and from these clones we retrieved the plasmidic DNA that was further analyzed through DNA sequencing. Among 13 retrieved clones, the one that was retrieved with the highest frequency (2/13) was expressed in HEK cells and tested by patch-clamp. This mutant version of BLINK2-HA shows an increased surface expression compared to wt. The % of GFP positive cells that responds to blue light is, in this case, > 40%. Our efforts are now focused on the characterization of this mutant, to understand the molecular basis of the increased membrane expression, and to make new rounds of selection to obtain mutants with even better trafficking.