Figure 4.

Physiological significance of post-initiation pausing. (A) HEK293 cells expressing GFP control, L4 wild type, or Δloop mutant were infected with lentiviruses encoding shRNA targeting endogenous L4 or scramble control. Cell viability was measured and quantified. Data are shown as means ± SD, n = 3. (B) A model for post-initiation pausing of ribosomes. After initiation, the nascent chain (red) traverses the exit tunnel (yellow). At the 5th codon position, the paused ribosome undergoes conformational changes, thereby facilitating elongation commitment by preventing nascent chain from off-route and abortive translation.