Forms a channel of about 1,7 nM through the cell membrane that allows diffusion of small hydrophilic molecules. The channel adopts an open conformation at low or zero membrane potential and a closed conformation at potentials above 20 mv. The open state has a weak anion selectivity whereas the closed state is cation-selective. Consists mainly of membrane-spanning sided beta-sheets. Belongs to the eukaryotic mitochondrial porin family. Highly divergent.