title: A requirement for RNA, protein and DNA synthesis in the establishment of DNA replicase activity in synchronized HeLa cells.
abstract: DNA replicase activity of synchronized cultures of HeLa cells was assayed by a permeable cell technique during normal S-phase and under conditions of restricted RNA, protein, or DNA synthesis. Inhibition studies with puromycin, cycloheximide, actinomycin D, and 2-mercapto-1-(beta-4-pyridethyl)benzimidazole revealed that the establishment as well as the maintenance of DNA replicase activity in S-phase cells was dependent on the continued synthesis of both RNA and protein. Measurements during limitation of DNA replication by hydroxyurea, cytosine arabinoside, or restricted availability of thymidine indicate that a low level of DNA synthesis is required to activate or assemble some subunits of DNA replicase. Evidence for the existence of short-lived RNA and protein factors essential for DNA replicase activity is discussed.
mesh_terms: D002455:Cell Division / Q000187:drug effects; D003513:Cycloheximide / Q000494:pharmacology; D004254:DNA Nucleotidyltransferases / Q000378:metabolism*; D004261:DNA Replication / Q000187:drug effects; D004273:DNA, Neoplasm / Q000096:biosynthesis*; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism*; D008727:Methotrexate / Q000494:pharmacology; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D014176:Protein Biosynthesis / Q000187:drug effects; D011691:Puromycin / Q000494:pharmacology; D012334:RNA, Neoplasm / Q000096:biosynthesis*; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D012334:RNA, Neoplasm; D011691:Puromycin; D003513:Cycloheximide; D004254:DNA Nucleotidyltransferases; D008727:Methotrexate