Fig. 2. F-dexa–binding to the membrane of single AtT-20 cells quantified by FCS. Intensity fluctuations and the measured and calculated corresponding autocorrelation curves G() at the cell membrane position for representative F-dexa concentrations of (a) 25, (b) 80 and (c)120 nM. Data were fitted with the three component model, with the fixed diffusion times of ₁=0.05, ₂=3.6 and ₃=255 ms. The resulting fractions were f₁=0.61, f₂=0.26, and f₃=0.13 for 25 nM, f₁=0.55, f₂=0.16, and f₃=0.30 for 80 nM, and f₁=0.23, f₂=0.21, and f₃=0.56 for 120 nM.