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Figure 6.
Figure 6 Model for tRNA movement during the translocation
reaction. The coordinate transformations of the RSR, when
applied to the A- and P-site bound tRNAs (A), result in
hypothetical intermediates of the tRNAs during translocation (C,
E) and a plausible trajectory for the path of the tRNAs from the
A to the P and from the P to the E site. The corresponding state
of the 40S subunit and its movements are shown in the cartoon in
(B, D, F). The 40S subunit is shown on the left from the
intersubunit side, and the head domain on the right from the top
of the subunit. The crystallographically determined positions of
the tRNAs in A (cyan), P (green) and E (purple) sites and an
mRNA fragment (cyan) (Yusupov et al, 2001) are shown in (A) and
are included in (C, E) as references painted in gray. (C) Shows
the tRNAs in A (cyan) and P (green) sites after the coordinate
transformation of the RSR for the body/platform domains of the
40S subunit (D) has been applied. The rotation of the 40S
subunit is indicated by arrows, and the rotation axis at h27 of
18S rRNA by a star (D). The outline of the untransformed 40S (B)
is included in (D) by the red line. The tRNA positions are
further transformed (E) according to the additional movement of
the head domain (F). This rotation occurs around a rotation axis
through the neck of the 40S subunit (indicated by a star in
(F)). The red line in (F) indicates the outline of the 40S
subunit in (D).
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