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Figure 3.
Figure 3. Overall organization of the HDAg dimer. (a) Ca
trace of the peptide d12-60(Y). The three regions of the peptide
are color-coded: A pink; B green; and C purple. The two monomers
form an antiparallel coiled coil. The individual helix takes a
sharp bend at Pro49. (b) Ribbon diagram of the view in (a)
rotated 90° along the horizontal axis. The sidechains have been
added and the C region of the peptide (residues 50-60(Y)) has
been removed for clarity. Sidechains are color-coded:
hydrophobic, gray; polar, yellow; acidic, red; and basic, blue.
Although the majority of the hydrophobic sidechains are packed
in the interior of the coiled coil, Trp20 is flipped out of the
core of the long helix. The figure also illustrates that the two
helices clearly wrap around one another. (c) The amino-acid
sequence of the long helix formed from residues 12-48 displayed
in the antiparallel orientation of the peptide. The letters
above the amino-acid sequence represent the heptad repeat
(abcdefg)[n] where the a and d residues tend to be hydrophobic.
Residues involved in the heptad repeat at the a and d positions
are shown in bold.
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