Cytoplasmic mRNPs revisited: Singletons and condensates

Abstract

Cytoplasmic messenger ribonucleoprotein particles (mRNPs) represent the cellular transcriptome, and recent data have challenged our current understanding of their architecture, transport, and complexity before translation. Pre-translational mRNPs are composed of a single transcript, whereas P-bodies and stress granules are condensates. Both pre-translational mRNPs and actively translating mRNPs seem to adopt a linear rather than a closed-loop configuration. Moreover, assembly of pre-translational mRNPs in physical RNA regulons is an unlikely event, and co-regulated translation may occur locally following extracellular cues. We envisage a stochastic mRNP transport mechanism where translational repression of single mRNPs-in combination with microtubule-mediated cytoplasmic streaming and docking events-are prerequisites for local translation, rather than direct transport.

The role of secondary structures in the functioning of 3′ untranslated regions of mRNA

“…Pre‐translational mRNPs are elongated and brunched structures, consisting of a single mRNA and a set of RNA‐binding proteins. [ 34 ] Components of mRNPs can be double‐stranded mRNA‐binding proteins such as Staufen (Stau). Two paralogs of Staufen have been identified in mammals—Staufen1 (STAU1) and Staufen2 (STAU2).…”