Steric blocking the N-terminus of SNAP(N) using AsLOV2 improves light regulation. A) Schematic of strategy to control interaction of SNAP(N) and SNAP(C) with AsLOV2. B) Quantification of labeling, comparing initial AsLOV2-fused version (left), and improved version (right, SNAP(N)(ΔN)), for cells kept in dark or light-treated (1s 461 nm pulse every 30s for 2h). Graph shows average and error (S.E.M.) of 3 biological replicates for graph at left, average and range for 2 for graph at right C) Strategy combining AsLOV2 steric blocking and dimerization. D) Quantification and images of Photo-SNAP-tag labeling in the cytosol in cells expressing LOV2-SNAP(N)(ΔN,L16A)-iLID and SspBmicro-SNAP(C). Graph shows average and error (S.E.M) of 3 biological replicates. E) Light/dark fold change and images of SNAP-Tag labeling (not normalized to intact SNAP-tag) in cells expressing mCh-LOV2-SNAP(N)(ΔN,L16A)-iLID(V416I) and plasma-membrane localized SspBmicro-SNAP(C)-CAAX. Graph reports average and error (S.E.M) of one experiment. 30 cells were quantified for each condition in all graphs. All scale bars, 10 μm.