Figure 4.

Mutational analysis of the Sec71TMD. In the MW71WS chimera of Figure 2, a variety of mutations were introduced into the TMD region. Putative TMDs are underlined. In the control (top), the highly hydrophobic region (HHR) and the flanking polar residues are marked with a box and asterisks, respectively. Sequences of the mutants constructed are shown below. These constructs were expressed in the wild-type (SNY9) and Δrer1 (SKY7) cells. Eight independent transformants were subjected to the halo assay and the secreted α-factor was quantified as described in MATERIALS AND METHODS. The ratio of the amount of secreted α-factor from the wild-type cells to that from the Δrer1 cells are shown on the right. Smaller numbers indicate better Rer1p-dependent ER localization.