What is the switch for coupling transcription and splicing? RNA Polymerase II C-terminal domain phosphorylation, phase separation and beyond.

Phosphorylation of the RNA polymerase II C-terminal domain (Pol II CTD) has important roles in the kinetic coupling of splicing with transcription, which is essential for many genes to maintain correct splicing patterns. However, because of the extensively repeated low complexity sequences of Pol II CTD, it was unclear how phosphorylation-dependent molecular interactions were able to provide sufficient specificity to spatiotemporally partition various cotranscriptional events. Here we try to view the molecular mechanisms governing cotranscriptional splicing from the role of phase separation based on recent studies showing the ability of Pol II CTD to form droplets. This article is categorized under:   RNA Processing > Splicing Regulation/Alternative Splicing   RNA Processing > Splicing Mechanisms   RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.