Molecular Grammar of RNA-binding Protein Interactions in Formation and Function of Ribonucleoprotein Complexes

Abstract

Ribonucleoproteins (RNPs) are macromolecular assemblies of proteins along RNA molecules to carry out specialized cellular processes. Understanding how RNA binding proteins (RBPs) and RNA sequences determine the interactions to form RNPs and ultimately steer biomolecular processes remains poorly understood. There is a mounting evidence that RNP assembly de-pends on the formation of a network of transient, multivalent RBP RNA and RBP RBP interac-tions, particularly between tyrosine residues from intrinsically disordered domains and argi-nine residues from RNA-binding domains of RBPs. Furthermore, RBPs, especially their intrin-sically disordered regions, are hotspots for posttranslational modification (PTM) sites. Alt-hough PTMs have been well catalogued, little is known about how these modifications regulate RNP assembly and function. Some initial studies introduced the concept of the so-called phos-pho-switch, in which RBPs require phosphorylation for condensation of larger RNP complexes, but it remains unclear how this contributes to the protein function and the pattern of selective protein binding to RNA molecules. This short review will take a look at what is currently known in the field of RNPs, their interactions, and the phase-separated biomolecular conden-sates, which are intimately connected to RNPs and are important for several key cell processes. Keywords: Ribonucleoproteins; RNA binding proteins; Multivalency; Intrinsically disordered proteins; Posttranslational modifications