The ribosomal GTPase, LepA or EF4, can promote back-translocation of tRNAs, thus reversing translocation. The cryo-EM structure of the ribosome with EF4 now suggests how such back-translocation can be allowed to occur and reveals that the tRNA is in an intermediate state that deviates from its canonical position.
- Sean R Connell
- Maya Topf
- Christian M T Spahn