PDZK1 directly regulates the function of organic cation/carnitine transporter OCTN2. Mol Pharmacol 67: 734–743. doi:10.1124/mol.104.002212 PubMed

Urinary excretion of cationic xenobiotics is believed to be me-diated by organic cation transporter (OCT and OCTN) families expressed on both basolateral and brush-border membranes of renal tubules, although the molecular mechanisms for targeting of these transporters to each membrane are poorly understood. Here, to examine the regulatory mechanisms for cell-surface expression and function of these transporters, we evaluated the interaction of these transporters with several PDZ proteins. A pull-down study using recombinant C-terminal proteins of OCTs and OCTNs identified a specific interaction of apical transporters OCTN1 and OCTN2, but not basolateral trans-porters OCT1 and OCT2, with PDZK1, intestinal and kidney-enriched PDZ protein, and Na/H exchanger regulatory factor 2 (also called E3KARP, SIP-1, or TKA-1). Both yeast two-hybri