title: A comparison of nucleoside (beta-S)triphosphates and nucleoside (gamma-S)triphosphates as suitable substrates for measuring transcription initiation in preparations of cell nuclei.
abstract: RNA chains initiated with nucleoside (beta-S)triphosphates and (gamma-S)triphosphates retain the thiol groups and can be separated from thiol-free RNA by chromatography on mercury-Sepharose. Thiol-containing mouse mammary tumor virus (MMTV) RNA synthesized by preparations of nuclei from virus-infected cells was quantitated by nucleic acid filter hybridization. With ATP beta S and GTP beta S, region-specific initiation of MMTV RNA chains was detected in the cell free system. However, with ATP gamma S and GTP gamma S, region-specific initiation was not clearly demonstrable. The nuclear preparations can also transfer thiol groups, presumably in the form of thiophosphate, from ATP gamma S or GTP gamma S onto preexisting RNA molecules; little or no thiol-transfer occurs with the two (beta-S)-analogues. The thiophosphate transfer activity apparently interferes with the measurement of RNA chain initiation with ATP gamma S and GTP gamma S.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D007700:Kinetics; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics; D051379:Mice; D009693:Nucleic Acid Hybridization; D012367:RNA, Viral / Q000235:genetics; D013329:Structure-Activity Relationship; D013872:Thionucleosides / Q000494:pharmacology*; D013873:Thionucleotides / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D012367:RNA, Viral; D013872:Thionucleosides; D013873:Thionucleotides; D012321:DNA-Directed RNA Polymerases