Figure 7.

A model for the role of yeast transmembrane proteins in resistance to cationic toxins and the emergence of SGE1 alleles. The model in (A) proposes the functions of ILT1 and SGE1 determined from this study. Sge1 functions in exporting cationic toxins, including CV and IILs, out of the cell through proton exchange. Alleles of SGE1 determine its protein abundance and the ability to tolerate high concentrations of cationic inhibitors. ILT1 may also directly or indirectly export cationic toxins out of the cytoplasm through the plasma membrane (P.M.). The dendogram in (B) proposes the evolutionary path for the emergence of the SGE1^SLS sequence from the ancestral SGE1^PLL allele. Extrac., Extracellular; Intrac., Intracellular.