SINGLE-PARTICLE TRACKING - THE DISTRIBUTION OF DIFFUSION-COEFFICIENTS

In single-particle tracking experiments, the diffusion coefficient D m ay be measured from the trajectory of an individual particle in the ce ll membrane. The statistical distribution of single-trajectory diffusi on coefficients is examined by Monte Carlo calculations. The width of this distribution may be useful as a measure of the heterogeneity of t he membrane and as a test of models of hindered diffusion in the membr ane. For some models, the distribution of the short-range diffusion co efficient is much narrower than the observed distribution for proteins diffusing in cell membranes. To aid in the analysis of single-particl e tracking measurements, the distribution of D is examined for various definitions of D and for various trajectory lengths.