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A structure-activity study of fatty acid interaction with mitochondrial uncoupling protein
P Jezek1, M Modrianský, K D Garlid
1Institute of Physiology, Department of Membrane Transport Biophysics, Academy of Sciences of the Czech Republic, Prague. jezek@sun1.biomed.cas.cz
Abstract:
Fatty acid (FA) uniport via mitochondrial uncoupling protein (UcP) was detected fluorometrically with PBFI, potassium-binding benzofuran phthalate and SPQ, 6-methoxy-N-(3-sulfopropyl)-quinolinium, indicating K+ and H+, respectively. The FA structural patterns required for FA flip-flop, UcP-mediated FA uniport, activation of UcP-mediated H+ transport in proteoliposomes, and inhibition of UcP-mediated Cl- uniport by FA, were identical. Positive responses were found exclusively with FA which were able to flip-flop in a protonated form across the membrane and no responses were found with 'inactive' FA lacking the flip-flop ability. The findings support the existence of FA cycling mechanism.