The high-conductance channels of yeast mitochondrial outer membranes: A planar bilayer study
- 33 Downloads
The high-conductance channels present in the outer membranes of wild-type and porin-less yeast mitochondria have been characterized electrophysiologically after incorporation in planar bilayer membranes. The most prominent activity was ascribed to a voltage-dependent, substaterich, cationic channel which generally inactivated at potentials positive in thecis compartment, in agreement with the observations from patch-clamp experiments on porin-less mitoplasts. This channel has been identified as the so-called “peptide-sensitive channel” (PSC). We also observed similar channels displaying either no inactivation, or inactivation at both positive and negative potentials. These latter properties match those already described for mammalian and yeast PSC, respectively. These different behaviors are tentatively explained as arising from the presence, or lack of, peptides bound to the PSC. Very high conductances, apparently due to cooperative gating, were frequently displayed. In wild-type membranes, activity ascribable to the porin was also observed.
Key wordsElectrophysiology peptide-sensitive channel mitochondrial megachannel porin planar bilayer yeast mitochondria
voltage-dependent anion channel (mitochondrial porin)
4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid
pre-cytochrome oxidase subunit IV
Unable to display preview. Download preview PDF.
- Colombini, M. (1994).Curr. Top. Membr. 42, 73–101.Google Scholar
- Halestrap, A. P. (1994). InMitochondria: DNA, Proteins and Disease (Darley-Usmar, V., and Schapira. A, H. V., eds.), Portland Press, pp. 113–142.Google Scholar
- Thieffry, M., Fèvre, F., Pelleschi, M., and Henry, J. -P. (1992b). InMolecular Biology of Mitochondrial Transport Systems (Forte, M., and Colombini, M., eds.), NATO ASI Series, Vol. H 83, Springer Verlag, Berlin, Heidelberg, pp. 209–219.Google Scholar
- Zoratti, M., SzabÒ, I., and De Pinto, V. (1992). InMolecular Biology of Mitochondrial Transport Systems (Forte, M., and Colombini, M., eds.), NATO ASI Series, Vol. H 83, Springer Verlag, Berlin, Heidelberg, pp. 153–168.Google Scholar