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Figure 1.
Figure 1. Ribbon drawing of the transthyretin structure.
(a) The structure of the dimer with monomer A colored in dark
gray and monomer B in light gray. The b-strands from each
monomer are denoted A-H as suggested by [Blake et al 1978]. Two
b-sheets (D-A-G-H and C-B-E-F) in each monomer form a b-barrel.
Two monomers dimerize through an intermolecular main-chain
interaction involving the H-strands from each monomer to form a
continuous eight-stranded b-sheet. The two paths of the FG-loop
in the B monomer are shown in red. (b) The structure of the
tetramer generated by applying the 2-fold crystallographic
symmetry operator on the dimer in the asymmetric unit. The two
dimers interact through hydrophobic contacts involving the loop
regions between b-strands G and H and b-strands A and B. The
thyroxine-binding sites are situated in one large hydrophobic
channel formed between the two dimers. The positions of 36
buried water molecules are indicated as blue spheres. The
pictures were generated using the program MOLSCRIPT [Kraulis
1991] and RENDER [Merritt and Bacon 1997].
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