Voltage-dependent anion channel
Eukaryotic porin | |||||||||
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TCDB 1.B.8 | | ||||||||
OPM superfamily | 189 | ||||||||
OPM protein | 3emn | ||||||||
CDD | cd07306 | ||||||||
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Voltage-dependent anion channels, or mitochondrial porins, are a class of
This major protein of the outer
Structure
This protein contains about 280 amino acids and forms a beta barrel which spans the mitochondrial outer membrane.[11][12]
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.[10]
Mechanism
At membrane potentials exceeding 30 mV (positive or negative), VDAC assumes a closed state, and transitions to its open state once the
Biological function
The voltage-dependent ion channel plays a key role in regulating metabolic and energetic flux across the outer mitochondrial membrane. It is involved in the transport of
Disease relevance
VDAC has also been shown to play a role in
Examples
Yeast contains two members of this family (genes POR1 and POR2); vertebrates have at least three members (genes VDAC1, VDAC2 and VDAC3).[11]
Humans, like most higher eukaryotes, encode three different VDACs; VDAC1, VDAC2, and VDAC3. Together with TOMM40 and TOMM40L they represent a family of evolutionarily related β-barrels.[22]
Plants have the largest number of VDACs. Arabidopsis encode four different VDACs but this number can be larger in other species.[23]
References
- PMID 17524423.
- S2CID 38314888.
- PMID 21986486.
- S2CID 3391282.
- PMID 21637820.
- PMID 8031826.
- PMID 1384178.
- S2CID 2199583.
- S2CID 10219032.
- ^ PMID 20708406.
- ^ PMID 8812436.
- PMID 20450883.
- ^ S2CID 38314888.
- ^ PMID 8744209.
- PMID 7685903.
- S2CID 33628015.
- PMID 16307870.
- PMID 12022949.
- PMID 15456403.
- S2CID 4423304.
- PMID 11266442.
- PMID 22178864.
- PMID 22155681.
External links
- Voltage-Dependent+Anion+Channels at the U.S. National Library of Medicine Medical Subject Headings (MeSH)