FIGURE 3.

Arginine residues inhibit rescue of a G251V processing mutant with tariquidar and cyclosporine A. A, whole cell SDS extracts of cells expressing P-gp processing mutant G251V, G251V/I868R, or G251V/Y307R in the presence of various concentrations of tariquidar or cyclosporine A were subjected to immunoblot analysis. The positions of mature and immature P-gps are indicated. B, the level of mature P-gp relative to total was determined. Each value is the mean ± S.D. (n = 3–5). An asterisk indicates significant difference (p < 0.001) relative to samples incubated in the absence of drugs.