the three vdac isoforms (vdac1, vdac2, and vdac3) have highly conserved dna sequences as well as 3d structures forming a wide β-barrel structure, inside of which the alpha helical n-terminal segment resides to partially close the pore. vdac1's structure was solved by 3 independent labs by x-ray crystallography, nuclear magnetic resonance (nmr) spectroscopy, or a combination of both. two of these structural studies were used to determine human vdac1 (hvdac1) structure while x-ray crystallography was used to solve murine vdac1 (mvdac1) structure that differs from hvdac1 by only two residues. these determined structures aligned with earlier circular dichorism studies that predicted the presence of alpha helix and β-strand domains.