Voltage-dependent anion channel of the outer mitochondrial membrane
The voltage-dependent anion channel (VDAC) regulates the flux of mostly anionic metabolites through the outer mitochondrial membrane, which is highly permeable to small molecules. VDAC is the most abundant protein in the outer membrane, and membrane potentials can toggle VDAC between open or high-conducting and closed or low-conducting forms. VDAC binds to and is regulated in part by hexokinase, an interaction that renders mitochondria less susceptible to pro-apoptotic signals, most likely by intefering with VDAC's capability to respond to Bcl-2 family proteins. While VDAC appears to play a key role in mitochondrially induced cell death, a proposed involvement in forming the mitochondrial permeability transition pore, which is characteristic for damaged mitochondria and apoptosis, has been challenged by more recent studies.