X-Ray Analysis of Prokaryotic and Eukaryotic Ribosomes - Biophysical Approaches to Translational Control of Gene Expression - page 6

a b

5 30S

3

7

50S

2

6

4

9

8

1

10

30S head

+12

-18

0 Å 4 Å 8 Å

Head

c d

Beak

1.8 Å

mRNA 5 ′

3.0 Å

+8

Platform

+9

+10

2.1 Å

mRNA 3'

Body

Spur

e f

Head

Head

Platform Platform

3.0 Å

Shoulder Shoulder

cognate A-tRNA

vacant A-site

Spur

Spur

near-cognate A-tRNA

Fig. 1.3 View of mRNA and tRNA interactions with the ribosome. ( a ) Cross-section of the
ribosome at the level of mRNA showing interactions between mRNA and the following ribosomal
elements: (1) Shine-Dalgarno sequence of the 3¢ of 16S rRNA; (2) ribosomal proteins S11 and
S18; (3) loop of helix 23b (16S rRNA); (4) A1507 of 16S rRNA; (5) interaction with modified