In yeast, Ca2+ and octylguanidine interact with porin (VDAC) preventing the mitochondrial permeability transition

In yeast, Ca(2+) and long chain alkylguanidines interact with mitochondria modulating the opening of the yeast mitochondrial unspecific channel. Mammalians possess a similar structure, the mitochondrial permeability transition pore. The composition of these pores is under debate. Among other components, the voltage-dependent anion channel has been proposed as a component of either pore. In yeast from an industrial strain, octylguanidine and calcium closed the yeast mitochondrial unspecific channel. Here, the effects of the cations Ca(2+) or octylguanidine and the voltage-dependent anion channel effector decavanadate were evaluated in yeast mitochondria from either a wild type or a voltage-dependent anion channel deletion laboratory strain. It was observed that in the absence of voltage-dependent anion channel, the yeast mitochondrial unspecific channel was desensitized to Ca(2+), octylguanidine or decavanadate but remained sensitive to phosphate. It is thus suggested that in yeast mitochondria, the voltage-dependent anion channel has a cation binding site where Ca(2+) and octylguanidine interact, conferring cation sensitivity to the yeast mitochondrial unspecific channel.