title: R-loop mapping of calf-thymus RNA polymerase II. Transcripts in vitro on restriction fragments of adenovirus 2 DNA.
abstract: Nascent RNA, synthesized by calf thymus ENA polymerase II on the restriction endonuclease EcoRI fragment A and BamHI fragment B of adenovirus 2 DNA, was rehybridized to the template strand under conditions allowing transcription R-loop formation. Hybrids, visualized by electron microscopy, were found in looped and in branched configurations, the former being abundant, with an average loop number of roughly four per EcoRI fragment A and three per BamHI fragment B. Frequency distributions of transcription R-loops, synthesized on identical restriction fragments for different periods of time, showed similar patterns, thus pointing to a nonrandom type of transcription. A comparison of the frequency distribution of R-loops seen on the two overlapping restriction fragments reveals reasonable coincidence in the loop pattern in one out of the four possible fragment orientations, permitting correlation of the transcription R-loop pattern with the physical map of the adenovirus 2 DNA. Comparison of start sites tentatively mapped in vitro with the known promoters for RNA polymerase II in vivo suggests that a major transcription site in vitro is located in close proximity to, or identical with, two promoters in vivo at 16.1 and 16.5 map units.
mesh_terms: D000256:Adenoviridae; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D004262:DNA Restriction Enzymes; D004279:DNA, Viral / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D012319:RNA Polymerase II / Q000378:metabolism*; D013950:Thymus Gland / Q000201:enzymology; D014158:Transcription, Genetic
chemical_list: D004279:DNA, Viral; D012319:RNA Polymerase II; D012321:DNA-Directed RNA Polymerases; D004262:DNA Restriction Enzymes