(A) Example of experimental tracking of Rad52 molecules visiting a double-strand break (DSB) focus. Different connected traces correspond to distinct Rad52 molecules. (B) Example trajectory of a particle visiting the focus from simulations in the PBM (left) and LPM (right). The simulated trajectories are visually similar to the data in B. (C) Displacement histogram (jump sizes) for the PBM, LPM and experiments, for an interval ms. D. Displacement histogram for the PBM for small values of (top) and high values (bottom). Here we varied the interval from ms (top) to ms (bottom). (E) Hypothesis testing using a two sided KS-test, comparing the displacement histogram of a free diffusion process (black line in D) and the displacement histogram of diffusion inside the focus (green line in D). Parameters are the same as in (D) was varied from 1 to 25 ms. (F) Effective diffusion coefficient as a function of distance to the focus center , estimated from simulations of the PBM calculating in each radial segment. (G) Particle density as a function of , estimated from simulations of the PBM. Error bars are standard errors on the mean. (H) Relation between the ratio versus the ratio of densities inside and outside the focus (From Equation 11), both estimated from simulations of the PBM (green crosses), compared to the identity prediction (Equation 12, black line). Blue cross shows the experimental observation for Rad52 in DSB loci (see text related to Figure 7 and Table S1 in Miné-Hattab et al., 2021). Parameter values as in Table 1 except: for B; for B-C; , and for D-E, for D, for F-H. In H we varied –, – s-1, and –. See Figure 2—source data 1.