Forms a channel through the mitochondrial outer membrane that allows diffusion of small hydrophilic molecules. Interacts with ARMC12 in a TBC1D21-dependent manner (By similarity). May localize to non-mitochondrial membranes. 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.