  We have developed a new model to describe FRET efficiency (E FRET) between
freely-diffusing membrane probes in phase-separated bilayers (Finite
Phase-separation FRET, or FP-FRET), that in principle applies to any system
where phase domain dimensions are larger than ~Ro . Here we use Monte Carlo
techniques to simulate E FRET for a range of probe partitioning behaviors and
domain sizes, and then fit the simulated data to the FP-FRET model to recover
simulation parameters. We find that FP-FRET can determine domain size to within
5% of simulated values for domain diameters up to ~ 5Ro, and to within 15% for
diameters up to ~ 20Ro . We also investigated the performance of the model in
cases where specific model assumptions are not valid.
