Based on a genomic microscopy screen (Buchan et al, 2013, Cell), we have recently discovered a novel means by which P-bodies in yeast are assembled (Fernandes et al, 2020, NAR). Specifically, the mRNA RPS28B recruits a known P-body assembly protein (Edc3) to it’s unusually long 3’UTR. In turn, Edc3 interacts with nascently synthesized Rps28 protein, a protein interaction which occurs significantly more poorly when the RPS28B 3’UTR and ORF are located in trans on separate mRNAs. The Rps28-Edc3 protein interaction in turn stimulates P-body assembly via an unclear mechanism, which remains an area of current interest.

This work is interesting for two key reasons. It is the first description of a cytoplasmic RNA-protein granule being nucleated by a specific mRNA, and suggests other RNP granules likely harbor key RNA scaffolds (e.g. NEAT1 lncRNA with parapseckles is another clear example in the nucleus). More broadly, in line with earlier work from the Mayr lab (Sloane Kettering), our study suggests 3’UTRs may facilitate nascent protein interactions, that in turn affect nascent protein function.