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.

• MeSH
• Models, Biological MeSH
• Electrophoresis MeSH
• Ion Channels metabolism   MeSH
• Humans MeSH
• Mitochondrial Proteins metabolism   MeSH
• Protons MeSH
• Uncoupling Protein 1 MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Research Support, N.I.H., Extramural MeSH
• Names of Substances
• Ion Channels MeSH
• Mitochondrial Proteins MeSH
• Protons MeSH
• Uncoupling Protein 1 MeSH

The presence of plant-uncoupling mitochondrial protein (PUMP), previously described by Vercesi et al. (1995), was screened in mitochondria of various organs or tissues of several plant species. This was done functionally, by monitoring purine nucleotide-sensitive linoleic acid-induced uncoupling, or by Western blots. The following findings were established: (1) PUMP was found in most of the higher plants tested; (2) since ATP inhibition of linoleic acid-induced membrane potential decrease varied, PUMP content might differ in different plant tissues, as observed with mitochondria from maize roots, maize seeds, spinach leaves, wheat shoots, carrot roots, cauliflower, broccoli, maize shoots, turnip root, and potato calli. Western blots also indicated PUMP presence in oat shoots, carnation petals, onion bulbs, red beet root, green cabbage, and Sedum leaves. (3) PUMP was not detected in mushrooms. We conclude that PUMP is likely present in the mitochondria of organs and tissues of all higher plants.

• MeSH
• Adenosine Triphosphate metabolism   pharmacology   MeSH
• Species Specificity MeSH
• Ion Channels metabolism   MeSH
• Linoleic Acid pharmacology   MeSH
• Membrane Potential, Mitochondrial drug effects   MeSH
• Mitochondrial Proteins metabolism   MeSH
• Mitochondria metabolism   MeSH
• Plant Proteins metabolism   MeSH
• Plants drug effects   metabolism   MeSH
• Uncoupling Agents pharmacology   MeSH
• Oxygen Consumption MeSH
• Tissue Distribution MeSH
• Uncoupling Protein 1 MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Adenosine Triphosphate MeSH
• Ion Channels MeSH
• Linoleic Acid MeSH
• Mitochondrial Proteins MeSH
• Plant Proteins MeSH
• Uncoupling Agents MeSH
• Uncoupling Protein 1 MeSH