Voltage-dependent anion channels (VDACs) are a class of porin ion channel located on the outer mitochondrial membrane. This major protein of the outer mitochondrial membrane of eukaryotes forms a voltage-dependent anion-selective channel (VDAC) that behaves as a general diffusion pore for small hydrophilic molecules. The channel adopts an open conformation at low or zero membrane potential and a closed conformation at potentials above 30-40 mV. VDAC facilitates the exchange of ions and molecules between mitochondria and cytosol and is regulated by the interactions with other proteins and small molecules. The voltage-dependent ion channel plays a key role in regulating metabolic and energetic flux across the outer mitochondrial membrane. Additionally, VDAC is an important regulator of Ca2+ transport in and out of the mitochondria.