Zinc is a potent reversible inhibitor of the pH-dependent anion-conducting channel in the mitochondrial inner membrane, 50% inhibition was produced by 1.5 microM added Zn2+ at which point free Zn2+ was < or = 10(-8) M. Inhibition by Zn2+ is rapid but can be prevented or rapidly reversed by excess EDTA. Concentrations of Zn2+ higher than 4 microM caused reversal of inhibition to a variable extent depending on the anion. Under these conditions Zn2+ did not inhibit ribose entry, the phosphate transporter, or the pH-insensitive component of the NO3- uniport.
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Inorganic phosphate is the major component of the thermostable cytoplasmic fraction which stimulates mitochondrial anion uniport.
Biochim Biophys Acta
November 1993
Department of Biochemistry, National University of Singapore.
A low molecular weight thermostable cytoplasmic fraction isolated from rat liver homogenate when pre-incubated with mitochondria increases the rate at which anions enter mitochondria via the pH-dependent anion-conducting channel in the inner membrane. The crude fraction obtained by centrifuging and heating the liver homogenate was purified by gel filtration and chromatography on DEAE-cellulose. The resulting factor is stable to heating at 100 degrees C, freeze-drying and extremes of pH.
View Article and Find Full Text PDFThe pH-dependent anion-conducting channel of the mitochondrial inner membrane is potently inhibited by zinc ions.
FEBS Lett
September 1993
Department of Biochemistry, Faculty of Medicine, National University of Singapore.
Zinc is a potent reversible inhibitor of the pH-dependent anion-conducting channel in the mitochondrial inner membrane, 50% inhibition was produced by 1.5 microM added Zn2+ at which point free Zn2+ was < or = 10(-8) M. Inhibition by Zn2+ is rapid but can be prevented or rapidly reversed by excess EDTA.
View Article and Find Full Text PDFEffect of buffers and osmolality on anion uniport across the mitochondrial inner membrane.
Biochim Biophys Acta
June 1993
Department of Biochemistry, National University of Singapore.
The effects of buffers and osmolality of the suspending medium on the pH-dependent anion uniport across the inner membrane of isolated rat liver mitochondria have been studied using the light scattering technique to measure passive osmotic swelling. In contrast to some other transport processes the rates of entry of chloride and other anions via the anion-conducting channel decreased steeply with increasing solute concentration. This effect appears to be a result of increased osmolality or decreased matrix volume rather than inhibition by the anion since it was also produced by increasing the osmolality by addition of non-penetrant solutes.
View Article and Find Full Text PDFPalmitoyl-CoA inhibits the mitochondrial inner membrane anion-conducting channel.
FEBS Lett
August 1988
School of Biological Sciences, University of East Anglia, Norwich, England.
Palmitoyl-CoA is shown here to inhibit the pH-dependent anion-conducting channel (IMAC) in the inner membrane of rat liver mitochondria, with half-maximal inhibition at 2.4 microM. It has little effect on the transport of ribose, thiocyanate and glutamate.
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