Figure 8.

Conserved lysine residues near the entry to the sterol-binding pocket are important for Lam4S2-mediated sterol transport. A, side and top (90° rotated) views of sterol-bound Lam4S2 are shown, color-coded as indicated by the scale bar to reveal the extent of conservation determined by ConSurf analysis. The sterol ligand is shown in stick representation in magenta. The lysine residues under investigation are indicated. B, sterol transport assay with WT and single mutants of Lam4S2 using anionic donor and acceptor vesicles and 0.05 μm protein (final concentration). Assay conditions are as described in Fig. 4B, condition e. The traces are normalized to the plateau value of FRET determined as described under “Experimental procedures”. C, quantification of transport rates for single mutants. D, sterol transport assay with double mutants as for B. E, quantification of transport rates for double mutants. Dotted lines (B and D) represent S.E. of three independent experiments. Individual measurements are shown in the scatter dot plots (C and E) along with the mean and S.D. (error bars).