The yeast Saccharomyces cerevisiae exhibits a phenotype homologous to mammalian multidrug resistance, termed pleiotropic drug resistance (Pdr). S. cerevisiae PDR genes include two major types of molecules: transcription factors, and their targets, such as the ABC transporter PDR5. We have recently identified the ABC transporter YOR1 (yeast oligomycin resistance 1). Yor1p displays homology to several known ABC transporters including the cystic fibrosis transmembrane conductance regulator (CFTR). An interesting feature of these ABC transporters is a conserved phenylalanine residue present in the first nucleotide binding domain, which when deleted in-frame from CFTR is the defect present in 60% of patients with cystic fibrosis. A deletion of the analogous phenylalanine in Yor1p (F670) has been constructed and renders Yor1p non-functional. Indirect immunofluorescence indicates a plasma membrane localization for Yor1p, while a fractionation procedure that enriches for vacuoles indicates it is present in certain vacuolar fractions. We are presently addressing the notion that the plasma membrane may be the site of function for Yor1p, while the vacuole may be a site for turnover. These techniques are also being used to determine the subcellular localization of *delta*F670 Yor1p. Additionally, Yor1p confers resistance to a second cytotoxic agent that is structurally unrelated to oligomycin, venturicidin, raising the possibility that Yor1p is a multidrug transporter.