The sat-1 transporter mediates sulfate/bicarbonate/oxalate anion exchange in vivo at the basolateral membrane of the kidney proximal tubule. Here, we show two renal cell lines (MDCK and LLC-PK1 cells) which similarly target sat-1 exclusively to the basolateral membrane. To identify possible sorting determinants, truncations of the sat-1 cytoplasmic C-terminus were generated, fused to enhanced green fluorescence protein (EGFP) or the human IL2R -chain (Tac) protein and both fusion constructs were transiently transfected into MDCK cells. Confocal microscopy revealed the removal of the last three residues on the sat-1 C-terminus, a putative PDZ domain, had no effect on the basolateral sorting in MDCK cells, nor an effect on sulfate transport in Xenopus oocytes. Removal of the last 30 residues led to an intracellular expression for the GFP fusion protein and an apical expression for the Tac fusion protein, suggesting a possible sorting motif lies between the last 3 and 30 residues of the sat-1 C-terminus. Elimination of a dileucine motif at position 677/678 resulted in the loss of basolateral sorting, suggesting this motif is required for sat-1 targeting to the basolateral membrane. This post-translational mechanism may be important for the regulation of sulfate reabsorption and oxalate secretion by sat-1 in the kidney proximal tubule.