Forms a channel through the mitochondrial outer membrane and also the plasma membrane (By similarity). The channel at the outer mitochondrial membrane allows diffusion of small hydrophilic molecules; in the plasma membrane it is involved in cell volume regulation and apoptosis (By similarity). It adopts an open conformation at low or zero membrane potential and a closed conformation at potentials above 30-40 mV (By similarity). The open state has a weak anion selectivity whereas the closed state is cation-selective (By similarity). In depolarized mitochondria, acts downstream of park to promote mitophagy or prevent apoptosis; polyubiquitination by park promotes mitophagy, while monoubiquitination by park decreases mitochondrial calcium influx which ultimately inhibits apoptosis (PubMed:32047033). Interacts with hexokinases. Expressed throughout development, highest levels are in embryos and pupae. Consists mainly of membrane-spanning sided beta-sheets. Ubiquitinated (PubMed:32047033). Undergoes monoubiquitination and polyubiquitination by park; monoubiquitination at Lys-273 inhibits apoptosis, whereas polyubiquitination at Lys-11, Lys-19, Lys-52 and Lys-109 may promote mitophagy (PubMed:32047033). Belongs to the eukaryotic mitochondrial porin family.