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Figure 2.
Fig. 2. Stereo view of the superposition of FK and TPR
domains. (a) Two FKBP domains of FKBP51 and FKBP52 were
superimposed onto FKBP12. FKBP12 (green), 51-FK1 (blue), and
52-FK1 (red) are similar. The structures of 51-FK2 (cyan) and
52-FK2 (yellow) are more closed than the others. (b) TPR domains
are superimposed onto the TPR domains of FKBP52. FKBP52 is shown
in yellow, FKBP51 is shown in cyan, Hop is shown in green, Cyp40
is shown in purple, and PP5 is shown in pink. The conformations
of all the TPR domains are similar, containing six  -helices
( 1- 6). The orientations of
the extra -helix ( 7) are
different. (c) Superposition of the structures of TPR domains
and the 7-helixes of FKBP51
(blue) and FKBP52 (yellow). Gln-333, Phe-335, and Ala-365 of
FKBP52 are replaced by Arg-331, Tyr-333, and Leu-363 in FKBP51,
which may be responsible for the differential binding pattern of
FKBPs to Hsp90. The side chain of Ile-400 of FKBP52,
corresponding to Ala-398 of FKBP51, will clash with Phe-369, and
this may cause the different orientations of the 7-helix.
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