During translation, tRNAs enter the ribosome and then move sequentially through three sites, known as A, P and E, as they transfer their attached amino acids onto the growing peptide chain. How the ribosome facilitates tRNA translocation between the sites remains largely unknown. Now a study uses multiparticle cryoelectron microscopy of a ribosome bound to the translation elongation factor, EF-G, to get information about tRNA movement. It identifies two new substates and sees that translocation is linked to unratcheting of the 30S ribosomal subunit.
- Andreas H. Ratje
- Justus Loerke
- Christian M. T. Spahn
