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. 2020 Nov 17;10:19954. doi: 10.1038/s41598-020-75814-y

Figure 2.

Figure 2

Fitting SPT experiments. (a) Raw image of a COS-7 cell expressing GFP-Nrx1β sparsely labeled with Atto647N-conjugated GFP nanobody (white signal). (b) Image of simulated molecules in the same geometry. Rectangles highlight the interface between the cellular region with freely diffusing GFP-Nrx1β molecules (blue outline), and the contact region with a cell expressing Nlg1-mcherry (yellow outline). On the right, a zoom on this ROI shows single molecule trajectories for both experiments and simulations. The diffusion coefficient expressed in log scale is color coded. (c) Distributions of GFP-Nrx1β diffusion coefficients for experiments (circles, average ± sem of 3 cells, 4145 trajectories in contact and 4867 outside contacts) and simulations (dashed lines, 5 repetitions, 8757 trajectories in contact and 2645 trajectories outside contacts) on a semi-log plot. The Spearman correlation coefficient comparing experiment and simulation was r = 0.85 (P < 0.001, n = 36 bins) for contact regions, and r = 0.81 (P < 0.001, n = 36 bins) for outside regions. (d) Representative examples of single molecule trajectories at the interface: (left) a molecule escapes the contact and diffuses out freely, or enters the contact and gets trapped; (right) a molecule stays stuck in the contact with low diffusion, or bounces on the contact without entering it.