VARIABLE PAUSE POSITIONS OF RNA-POLYMERASE-II LIE PROXIMAL TO THE C-MYC PROMOTER IRRESPECTIVE OF TRANSCRIPTIONAL ACTIVITY

Transcriptional activation of the c-myc proto-oncogene is mediated by the transition of promoter proximal, paused RNA polymerase II (pol II) into a processive transcription mode, Using a transcription assay whi ch allows the high resolution mapping of transcriptional complexes in intact nuclei, we have characterized the promoter proximal pause posit ions of pol II, Pol II paused in a nucleosome-free region close to the transcription start site as well as further downstream, between posit ions +17 and +52, These pause positions were detected in both transcri ptionally active and inactive c-myc genes, Pharmacological inhibition of the C-terminal phosphorylation of the large subunit of pol II did n ot affect the paused transcription complexes, but had an inhibitory ef fect on transcription of nucleosomal DNA downstream of position +150, The different properties of pol II proximal and distal to the promoter suggest a model in which c-myc transcription is regulated by the acti vation of promoter bound polymerases.