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. Author manuscript; available in PMC: 2015 Jun 12.
Published in final edited form as: Cell Rep. 2014 May 15;7(5):1521–1533. doi: 10.1016/j.celrep.2014.04.033

Figure 4. Proline must be positioned at codon 18 to precipitate stalling.

Figure 4

(A) The P18A (Pro18 to Ala) mutant (n = 231), despite retaining Pro19, allows 50% of ribosomes to translate past codon 22. (B) The lifetimes of each state is similar to the wild-type SecM up to codon 17, but the non-rotated state lifetimes quickly recover thereafter and lengthening of the rotated state lifetimes is less. (C) Translating SecM with total tRNA charged with Aze (azetidine-2-carboxylic acid) in place of Pro prevents stalling (n = 293). (D) The time to translate each codon is very similar to the P18A mutant. (E) The P19A mutant (n = 276) behaves exactly like the wild-type sequence, inducing stalling between codons 18~22. (F) The lifetimes per codon profile of P19A is similar to the wild-type SecM. Lifetimes are fitted to single-exponential distributions and error bars represent s.e.m.