| | Channel character of uncoupling protein-mediated transportEdited by Adam Szewczyk Received 13 November 2009; received in revised form 23 February 2010; accepted 26 February 2010. published online 04 March 2010. Abstract Mitochondrial uncoupling proteins (UCPs) are pure anion uniporters, which mediate fatty acid (FA) uniport leading to FA cycling. Protonated FAs then flip-flop back across the lipid bilayer. An existence of pure proton channel in UCPs is excluded by the equivalent flux-voltage dependencies for uniport of FAs and halide anions, which are best described by the Eyring barrier variant with a single energy well in the middle of two peaks. Experiments with FAs unable to flip and alkylsulfonates also support this view. Phylogenetically, UCPs took advantage of the common FA-uncoupling function of SLC25 family carriers and dropped their solute transport function. Abbreviations: ANT, adenine nucleotide transporter, i.e. ADP/ATP carrier, BLM, bilayer (black) lipid membrane, FA(s), fatty acid(s), FAOOH or FAOOH–COOH, fatty acid hydroperoxides, PUFAs, polyunsaturated fatty acids, PUMPn, plant uncoupling mitochondrial protein, isoform n, ROS, reactive oxygen species, SPQ, 6-methoxy-N-(3-sulfopropyl)-quinolinium, TEA, tetraethyl ammonium, TES, N-tris(hydroxymethyl)-methylamino-ethanesulfonic acid, UCP, UCPn, any uncoupling protein, isoform n a Department of Membrane Transport Biophysics, No. 75, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic b Department of Biology, Portland State University, Portland, Oregon, USA  Corresponding author. Address: Department of Membrane Transport Biophysics, No. 75, Institute of Physiology, Academy of Sciences of the Czech, Republic, Vídeňská 1083, CZ 14220 Prague, Czech Republic. Fax: +420 296442488.
PII: S0014-5793(10)00172-9 doi:10.1016/j.febslet.2010.02.068 © 2010 Federation of European Biochemical Societies | |
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ABSTRACT
