Voltage-Dependent Anion selective Channel maintains the permeability of the outer mitochondrial membrane and is relevant in bioenergetic metabolism and apoptosis. The structure of the protein was shown to be a β-barrel formed by 19 strands. The topology or sideness of the pore has been predicted with various approaches but a general consensus was never reached. This is an important issue since VDAC is considered receptor of Hexokinase and Bcl-2. We fused at VDAC1 C-terminus two tags separated by a caspase cleavage site. Activation in cellulo of caspases was used to eventually separate the two reporters. This experiment did not require the isolation of mitochondria and limited the possibility of outer membrane rupture due to similar procedures. Our results show that the C-terminus end of VDAC faces the mitochondrial inter-membrane space.
Tomasello, M. F., Guarino, F., Reina, S., Messina, A., & De Pinto, V. (2013). The Voltage-Dependent Anion selective Channel 1 (VDAC1) topography in the mitochondrial outer membrane as detected in intact cell. PLoS ONE, 8(12). https://doi.org/10.1371/journal.pone.0081522