FIGURE 4.

Global distributions of jump distances in the nuclear subcompartments. The distributions of jump distances occurring between subsequent frames (within 5.22 ms) are shown in panels A, C, and E for the three compartments. The distributions were fitted with a three-component model using the diffusion coefficients D₁ = 0.15 μm²/s (for the fixed fraction), D₂ = 0.8 μm²/s, and D₃ = 5 μm²/s. The data could not be fitted satisfactorily assuming only one or two diffusing components. The fraction of molecules in each mobility class varies strongly between compartments (see Table 1). In panels B, D, and F, the loss of observations over time was monitored for the different compartments. The jumps were binned into two classes: displacements <100 nm (corresponding to the twofold localization precision) and >100 nm. The limited compartment size of pericentric heterochromatin and the nucleolus makes the observation of large jumps less probable, and hence, very long jumps >700 nm were not considered.