@article{oai:repo.qst.go.jp:00043060,
 author = {Kimura, Hiroshi and Sugaya, Kimihiko and Cook, Peter and 菅谷 公彦},
 journal = {Journal of Cell Biology},
 month = {},
 note = {RNA polymerase II transcribes most eukaryotic genes. Its catalytic subunit was tagged with green fluorescent protein and expressed in Chinese hamster cells bearing a mutation in the same subunit; it complemented the defect and so was functional. Photobleaching revealed two kinetic fractions of polymerase in living nuclei: less than 75% moved rapidly, but less than 25% was transiently immobile (association t1/2 20min) and transcriptionally active, as incubation with 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole eliminated it. No immobile but inactive fraction was detected, providing little support for the existence of a stable holoenzyme, or the slow stepwise assembly of a preinitiation complex on promoters or the nuclear substructure. Actinomycin D decreased the rapidly moving fraction, suggesting that engaged polymerases stall at intercalated molecules while others initiate. When wild-type cells containing only the endogenous enzyme were incubated with 3H uridine nascent transcripts became saturated with tritium with similar kinetics (t1/2  14min). These data are consistent with a polymerase being mobile for one half to five sixths of a transcription cycle, and rapid assembly into the preinitiation complex. Then, most expressed transcription units would spend significant times unassociated with engaged polymerases.},
 pages = {777--782},
 title = {The transcription cycle of RNA polymerase II in living cells},
 volume = {159},
 year = {2002}
}