Functional Importance of Mobile Ribosomal Proteins

Figure 2

Different conformations of L1 stalk. The L1 protein is not resolved in these structures, and therefore, only the H76-78 of 23S rRNA (nucleotide 2093–2196) part of the stalk is shown and highlighted. An open conformation (green, PDB 2I2T [30]) is found in the ribosome lacking an E-site tRNA (red). When the tRNAs are in their A/P and P/E hybrid states, L1 stalk adopts a fully closed conformation (magenta, PDB 3R8S [31]). In the presence of a classical-state E-site tRNA, L1 stalk resides in between those conformations and thus becomes “half-closed” (blue, PDB 3I8I [32]). The A-site (yellow), P-site (orange), and E-site (red) tRNAs in their classical states and the 23S rRNA (gray) are taken from PDB 3I8I [32].