Structure
This protein contains about 280 amino acids and forms a beta barrel which spans span the mitochondrial outer membrane.
Since its discovery in 1976, extensive function and structure analysis of VDAC proteins has been conducted. A prominent feature of the pore emerged: when reconstituted into planar lipid bilayers, there is a voltage-dependent switch between an anion-selective high-conductance state with high metabolite flux and a cation-selective low-conductance state with limited passage of metabolites.
More than 30 years after its initial discovery, in 2008, three independent structural projects of VDAC-1 were completed. The first was solved by multi-dimensional NMR spectroscopy. The second applied a hybrid approach using crystallographic data. The third was for mouse VDAC-1 crystals determined by X-ray crystallographic techniques. The three projects of the 3D structures of VDAC-1 revealed many structural features. First, VDAC-1 represents a new structural class of outer membrane β-barrel proteins with an odd number of strands. Another aspect is that the negatively charged side chain of residue E73 is oriented towards the hydrophobic membrane environment. The 19-stranded 3D structure obtained under different experimental sources by three different laboratories fits the EM and AFM data from native membrane sources and represents a biologically relevant state of VDAC-1.
Read more about this topic: Voltage-dependent Anion Channel
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