FIGURE 2: Two alternative, non-mutually exclusive working models of lipid flippase function in antifungal drug resistance.

In Model 1, increased levels of PS (or other phospholipids) on the outer leaflet of the plasma membrane in the cdc50∆ mutant may change membrane structure in a way that promotes the interaction of certain drugs with their targets, thus enhancing drug-mediated inhibition of target activity. In Model 2, because lipid flippase activity is required for normal intracellular vesicle trafficking, vesicles containing specific drug targets may be incorrectly targeted, reducing correct drug target localization, impairing these pathways, and increasing sensitivity to the corresponding antifungal drugs. TGN: trans-Golgi network.