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Figure 4.
Helix packing perturbations in the EphA1tm dimer caused by
deprotonation of Glu^547 carboxyl group. A and B, ribbon
diagrams of the NMR-derived spatial structures of the EphA1tm
dimer before (A) and after (B) MD relaxation in explicit lipid
bilayer. The dimer structures (superimposed on one subunit)
obtained for EphA1tm embedded in the DMPC/DHPC bicelles at pH
4.3 and 6.3 are shown in light and dark gray, respectively. C
and D, the EphA1tm helix packing interface after MD relaxation
in explicit lipid bilayer. Hydrophobicity maps (on the left) for
EphA1tm helix surface with contour isolines encircling
hydrophobic regions with high values of molecular hydrophobicity
potential are covered by areas of dark points indicating the
N-terminal dimerization interface realized in the major
right-handed dimer conformation at pH 4.3 (C) and pH 6.3 (D). A
possible C-terminal dimerization interface implying a
left-handed crossing of the EphA1tm TM helices is highlighted by
dashed curved lines (D). The helix packing contact areas per
EphA1tm residue averaged over the equilibrium part (last 2 ns)
of restrained MD relaxation of the dimer structure are presented
at the right of the maps. The spreads of the contact area are
shown by bars. deg., degree.
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