Figure 4: Reversibility of CNBD blinking.

(a) An identical membrane imaged in presence of 100 μM cAMP (upper), then in 10 nM cAMP (middle), and after re-addition of 100 μM cAMP (lower). Single HS-AFM frames (left), average height topographies (centre) and the s.d. maps (right) of the movies are shown. Scale bar: 50 nm. Full colour scale: 3 nm. (b) Histograms of the s.d. of each original movie frame (n=200) consisting of 30,000 pixel at 100 μM cAMP (black), 10 nM cAMP (blue), and after re-introduction to 100 μM cAMP (red). An increase in the s.d. distributions reflects increasing height distributions. (c) Histograms of the s.d. maps of the movies (a, right). The more blinking molecules, the higher the height variability.