Molecular and cell-based assays, combined with mass spectrometry, high-throughput sequencing and computational analyses, will be used to determine cell/tissue-dependent and -independent functions of ribonucleosomes, as well as how protein modifications impact their assembly and activities. With the combined and internationally-leading expertise of our team, we are in a unique position to address how transcripts are organized in the nucleus by ribonucleosomes and how these complexes critically function in the regulated biogenesis of mRNA. Much like how the discovery and characterization of nucleosomes advanced our understanding of chromatin, transcriptional regulation and epigenetics, we anticipate our proposed research will be similarly transformative and provide unprecedented insight into the long-standing question of how the packaging of nuclear primary transcripts occurs and relates to the regulation of biogenesis and expression of mRNA.