porin

Mitochondrial outer membrane protein, also referred to as VDAC (Voltage Dependent Anion Channel). Represents a regulated gate between the cytosol and intramitochondrial compartments for the exchange of metabolites. Believed to occur as a dimer, this mostly beta sheet transmembrane protein forms a hydrophilic pore in the outer membrane allowing neutral molecules (up to 5 kDa) to diffuse in and out the mitochondrion.
last update, Dec 1999 - Claude Aflalo - suggestions are welcome...