  For some time now, we have been using a FRET-based strategy to make
high-resolution studies of phase behavior in ternary lipid-raft membrane
mixtures. Our FRET experiments can be carried out on ordinary, polydisperse
multilamellar vesicle suspensions, so we are able to prepare our samples
according to a procedure that was designed specifically to guard against
artifactual phase separation. In some respects (i.e., the number and nature of
two-phase regions observed), our phase diagrams are consistent with previously
published reports. However, in other respects (i.e., overall size of
miscibility gaps, phase boundary locations and their dependence on temperature)
there are clear differences. Here we present FRET data taken in
DOPC/DPPC/Cholesterol mixtures at 25.0, 35.0 and 45.0oC. Comparisons between
our results and previously reported phase boundaries suggest that lipid-raft
mixtures may be particularly susceptible to demixing effects during sample
preparation.
