RNA Structure and Function 277
Figure 7.28 Proteins mimic the structure and interactions of tRNA. A domain of EF-G (purple) mimics tRNA
and binds to the ribosomal A site. The complex between tRNA (red) and EF-Tu (yellow) is shown
for comparison. Release factor (RF) closely mimics the L-shape and electrostatic properties of
tRNA, even binding the ribosome through an anticodon mimic at the tip of its alpha-helical bundle
(blue loops)
(Reprinted from Ref. 76. © (1999), with permission from AAAS)
Figure 7.29 The structures of the ribosomal subunits. Interface views of the 50S (left) and 30S (right) subunits,
along with bound tRNAs (yellow, orange, and red, in the A, P, and E site halves of each subunit). The
subunits clamp together like the two parts of a shell, enclosing the tRNAs inside (one can visualize the
closed form by superimposing the corresponding tRNA molecules)
(Reprinted from Ref. 28. © (2001), with permission from AAAS)