Nat. Struct. Mol. Biol. doi:10.1038/nsmb.3351 (2017)

Many eukaryotic mRNAs are transported from the nucleus, where they are produced, to distal subcellular locations where they can be locally translated. In Saccharomyces cerevisiae, ASH1 mRNAs are moved to the tip of the daughter cell during mitosis, a process that requires She2p and She3p. Edelmann et al. have investigated the structures of ASH1 mRNA on its own, in the presence of She2p, and in the presence of She2p and a C-terminal fragment of She3p. In the absence of protein, the mRNA forms a straight but flexible stem–loop architecture; the presence of She2p leads to the formation of a large 'kink' in the structure of the mRNA, which is critical for transport. The addition of the C-terminal fragment of She3p did not alter the overall structure of the She2p–ASH1 mRNA complex, but further stabilized the complex via interactions with She2p and the mRNA. The authors identified several amino acids that appeared to be essential for mRNA recognition and binding, and they confirmed the importance of these protein–mRNA interactions in vivo. Additional work is needed to determine the structure of the entire She3p–She2p–ASH1 mRNA complex in the presence of myosin and to probe other possible physiological roles for the flexibility of the mRNA.