FIGURE 1.

Point mutations to IH2 inhibit P-gp maturation. A, model of P-gp showing the location of coupling helix IH2 between TMD1 and NBD2. The branched lines represent the glycosylation sites. B, wild-type and P-gp mutants (mutations to IH2 and flanking regions) were expressed in HEK 293 cells, and whole cell SDS extracts were subjected to immunoblot analysis. The positions of mature (170 kDa) and immature (150 kDa) forms of P-gp are shown. C, Percent Mature is the amount of mature protein relative to total P-gp. Each value is the mean ± S.D. obtained from three different transfections.