Figure 10.

Model showing trafficking step(s) impaired by vps mutations. Proposed impaired step(s) in transport from the Golgi to the vacuole are labeled with the corresponding vps mutations. Transport from the Golgi to the endosomal system is blocked in vps1Δ cells (Nothwehr et al., 1995); endosome-bound traffic, including Pma1-7, is redirected to the surface from the Golgi. In class E vps mutants, such as vps36 and vps27, there is defective anterograde transport from the prevacuolar compartment to the vacuole as well as defective retrograde transport to the Golgi (Piper et al., 1995; Nothwehr et al., 1996). In class E vps mutants, Pma1-7 is proposed to travel to the plasma membrane from the prevacuolar compartment via an early endosome. In vps8 cells, there is defective transport from the early endosome to the vacuole; movement of mutant Pma1 to the plasma membrane in vps8 is proposed to occur as a consequence of accumulation in an early endosome.