Figure 2.
Proposed sorting steps blocked by vps and other trafficking mutants analyzed in Table II. The sorting steps shown and the placement and grouping of mutants are based on a large number of studies (Raymond et al., 1992; Stack et al., 1995, and citations therein). In the Vps pathway cargo molecules are sorted at the late Golgi/TGN into transport vesicles that fuse with a PVC/ endosomal compartment. This latter step is blocked in many of the original class D vps mutants, such as vps45. Exit from the PVC for transport to the vacuole and for recycling back to the Golgi is thought to require the function of the class E mutants. Class C vps mutants block the final step of transport to the vacuole. Some of the sorting mutants analyzed in Table II are indicated with a question mark or are not shown in the figure (vps8, vps39, pep8, and dnm1). In these cases the placement in the sorting pathways is more ambiguous. Mutants showing synthetic growth phenotypes with apm3-Δ are indicated with an asterisk.