Figure 5.

Experimental LIESS–FCS recordings of the fluorescently tagged (Abberior STAR Red) GPI-SNAP protein in the plasma membrane of live PtK2 cells. (A) Representative confocal image of a portion of the cellular membrane indicating homogeneous distribution with rare bright and immobile clusters. Scale bar: 10 μm. (B) Representative correlation carpet of the simultaneous confocal (d_conf = 240 nm) and STED recordings (d_STED = 100 nm, measurement time of 70 s and 1.36 μm scan). (C) Values of D_rat resulting from the analysis of the correlation carpet with (D) frequency histogram indicating large fluctuation of D_rat. (E) Histogram of values of D_rat obtained from 5 different line scans on 5 different cells with a peak at D_rat = 0.6 and a broad distribution with values ranging from D_rat ≪1 (trapping) and D_rat = 0 (free) to D_rat > 1 (hop), confirming the strong variation in diffusion modes.