Cadmium sensitive/nickel resistant mutants and protein traffic networks centred on the vacuole and the Golgi. (a) Schematic representation of the endocytotic pathway, including targeting to (and formation of) the prevacuolar compartment (PVC; pathway I), and protein retrieval from the PVC to the late Golgi (pathway II). The Golgi-to-vacuole, carboxypeptidase Y (CPY) and alkaline phosphatase (ALP) pathways that, when disrupted, respectively lead to cadmium and nickel sensitivity are shown for comparison. Pathways whose disruption determines cadmium sensitivity but nickel resistance are indicated with red arrows; and pathways that cause cadmium or nickel specific sensitivity when disrupted are indicated with black and green arrows, respectively. The Y-shaped symbols indicate plasma membrane transporters whose deletion causes cadmium (#1; for example, Smf1) or nickel (#2; for example, Fur4 and Tna1) resistance; see Additional data file 2 for further details on the genes that are involved in these pathways. (b) Serial tenfold dilutions of mutant strains representative of pathway I and II assayed for their capacity to grow onto yeast extract-peptone-dextrose (YPD) plates supplemented with the indicated cadmium and nickel concentrations; the wild-type (WT) control strain is shown at the bottom of each panel.