Localization of C34-cholesterol in the bilayer.
(A–B) Stern-Volmer plots for the quenching of C34-cholesterol fluorescence by 5NS or 16NS in POPC (A) and POPC:Chol 2∶1 (B) LUV, using time-resolved fluorescence measurements. Each point is the average of three independent measures. The dashed lines are fittings of the Lehrer equation (eq. 4) to the experimental data, except for 16NS in POPC (eq. 3). (C) Depth of insertion of C34-cholesterol Trp residues in the membrane using SIMEXDA method , yielding an average location 16.8 Å away from the center of the bilayer for POPC and 18.0 Å for POPC:Chol 2∶1. Distributions’ half-width at half-height were 8.9 Å for POPC and 6.5 Å for POPC:Chol.