show Abstracthide AbstractIn this study, we aim to understand how the fates of stress-activated mRNAs are determined under stress conditions by isolating individual osmostress-activated mRNA species, quantitating the proteins associated in vivo with each of them, and analyzing how deletion of these proteins impact on the expression of stress-activated genes. By comparison with the proteome associated with individual not stress-related mRNA species, we show specific proteins to be preferentially binding to osmostress-activated mRNAs, notably members of the cytoplasmic Pat1 / Lsm1 – 7 complex. We evaluated the impact of this complex on the stress response by analyzing expression of osmostress-activated genes, production of osmo-protein and, mapping ribosome transit at single nucleotide resolution using 5'-phosphate sequencing of mRNAs in lsm1 and pat1 mutants. We conclude that our biochemical co-purification approach has successfully identified RNA-binding proteins with a particular role in regulating post-transcriptional expression of stress-activated mRNAs. Overall design: We performed 3 biologically independent 5PSeq experiments before stress (t0) and 30 minutes after osmotic stress (t 30).