On the Mechanism of Fatty Acid-induced Proton Transport by Mitochondrial Uncoupling Protein

• DOI: 10.1074/jbc.271.5.2615
• Publication Date: 2002-07-26T15:15:23Z
• Authors: Keith D. Garlid; David E. Orosz; Martin Modrianský; Stefano Vassanelli; Petr Jezek
• Keywords: Uncoupling Agents; Proton Transport; Transport protein; Chemiosmosis; Protonophore; Thermogenin; Electrochemical gradient

Uncoupling protein mediates electrophoretic transport of protons and anions across the inner membrane brown adipose tissue mitochondria. The mechanism site proton transport, by which fatty acids activate relationship between anion are unknown. We used fluorescent probes to measure H+ in vesicles reconstituted with purified uncoupling carried out a comparative study effects laurate its close analogue, undecanesulfonate. Undecanesulfonate was transported Km value similar that observed for as it activated transport. Both undecanesulfonate inhibited Cl− competitive kinetics. laurate-induced differed two important respects. (i) Laurate caused protein-mediated whereas did not. (ii) Lauric acid rapidly bilayer nonionic diffusion, undecanesulfonic infer role is induce because they can diffuse electroneutrally membrane. According this hypothesis, pure porter does not protons; rather designed enable behave cycling protonophores.