Fig. 4.

Mutations at linker sites improved ASAPs photostability. a Schematic diagram showing the constructs of ASAP2f and its mutant ASAP2f-LE. b ASAP2f-LE mutant expressed in neurons showed less photoconversion compared to original ASAP1 and ASAP2f. The fluorescence loss of ASAP2f-LE was no longer recoverable by 405-nm co-illumination. c Spontaneous recovery from photoswitching of the mutant in the dark. All imaging conditions were similar to that in Fig. 1b. d ASAP2f-LE showed lower voltage sensitivity in response to single APs. p = 0.04, t-test; n = 6 for ASAP2f, n = 6 for ASAP2f-LE