Steroidogenic acute regulatory protein (StAR) mediates cholesterol transport from the outer
to the inner mitochondrial membrane during steroid biosynthesis. The mechanism of StAR's
action is not established. To address mechanistic issues, we assessed the binding of StAR
to artificial membranes by fluorescence resonance energy transfer using endogenous StAR
tryptophan residues as the donor and dansyl-phosphatidylethanolamine in the bilayer as the
acceptor. Mixing StAR with dansyl-labeled vesicles composed of phosphatidylcholine …