Forms a channel through the mitochondrial outer membrane that allows diffusion of small hydrophilic molecules (By similarity). The channel 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). Binds various lipids, including the sphingolipid ceramide, the phospholipid phosphatidylcholine, and the sterol cholesterol (By similarity). Binding of ceramide promotes the Binding of ceramide promotes the mitochondrial outer membrane permeabilization (MOMP) apoptotic pathway (By similarity). Interacts with hexokinases (By similarity). Interacts with ARMC12 in a TBC1D21-dependent manner (By similarity). Interacts with KLC3 (By similarity). Interacts with SPATA33 (By similarity). Interacts with PPP3CC in a SPATA33-dependent manner (By similarity). May localize to non-mitochondrial membranes. Highly expressed in heart, kidney, brain and ascitic tumor with very low levels in liver. Expressed in the head region of epididymal sperm. Consists mainly of a membrane-spanning beta-barrel formed by 19 beta-strands. Ubiquitinated by PRKN during mitophagy, leading to its degradation and enhancement of mitophagy. Deubiquitinated by USP30. Belongs to the eukaryotic mitochondrial porin family.