Single-molecule imaging reveals RNA polymerase II dynamics and TAF1-dependent promoter-proximal pause release (opens in new tab)

Early transcriptional regulation is a major kinetic bottleneck in gene expression, yet the dynamics of RNA polymerase II in living cells remain poorly understood. Here, we use single-molecule imaging to quantify RNA polymerase II chromatin engagement in live human cells. We find that RNA polymerase II infrequently enters a long-lived binding state associated with productive elongation, with ~94% of chromatin-associated events dissociating within tens of seconds. Single-cell analysis reveals s...