Figure 5.

(a) Schematic of photochromic FRET in an anti-actin antibody co-labelled with Cy3 and NISO. (b) Intensity trace of Cy3 fluorescence over the course of five cycles of optical switching between the SP and MC states on the antibody. The trace serves as the internal reference waveform in the OLID-FRET analysis. (c) Intensity image of Cy3 fluorescence in the SP state of an NIH 3T3 cell stained with the co-labelled antibody. (d) Image of the correlation coefficients in an OLID-FRET-based analysis of the Cy3/NISO-labelled antibody in the image shown in figure 5c.