Channel character of uncoupling protein-mediated transport.
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.
Jezek
Petr
P
Department of Membrane Transport Biophysics, No. 75, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Jabůrek
Martin
M
Garlid
Keith D
KD
D000818:Animals; D004586:Electrophoresis; D006801:Humans; D007473:Ion Channels / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D008954:Models, Biological; D011522:Protons; D000071256:Uncoupling Protein 1
D007473:Ion Channels; D024101:Mitochondrial Proteins; D011522:Protons; D000071256:Uncoupling Protein 1