How cells get the message: dynamic assembly and function of mRNA–protein complexes

Key Points Global approaches are defining the full complement of proteins with RNA-binding capacity in living cells. RNA packaging by proteins begins during transcription and determines the fate of the RNA. RNA-binding proteins (RBPs) can act as 'molecular rulers', sorting RNAs according to their length. RBPs can link sequential and non-sequential processing steps. A future challenge is to define the composition of individual mRNPs at different stages of remodelling. RNA-binding proteins (RBPs) are crucial for guiding mRNAs through the many steps from transcription to translation and decay. This Review discusses recent insights into the repertoire of RBPs, how they package RNA molecules and how they can connect different processing steps. mRNA is packaged into ribonucleoprotein particles called mRNPs. A multitude of RNA-binding proteins as well as a host of associated proteins participate in the fate of mRNA from transcription and processing in the nucleus to translation and decay in the cytoplasm. Methodological innovations in cell biology and genome-wide high-throughput approaches have revealed an unexpected diversity of mRNA-associated proteins and unforeseen interconnections between mRNA-processing steps. Recent insights into mRNP formation in vivo have also highlighted the importance of mRNP packaging, which can sort RNAs on the basis of their length and determine mRNA fate through alternative mRNP assembly, processing and export pathways.