title: Characterization of an endogenous transcription inhibitor from Physarum polycephalum.
abstract: A substance has been purified from isolated nuclei of Physarum polycephalum by equilibrium and velocity gradient centrifugations, ion exchange chromatography and gel filtration which has a high molecular weight, can be labeled in vivo with 32P, is heat stable and resistant to amylases, proteases, nucleases and phosphodiesterase but is sensitive to phosphatases or hydrolysis. This material consists of phosphate and glycerol. It selectively inhibits in vitro transcription of RNA polymerases, predominantly the homologous enzyme A by binding to the enzyme. In the presence of this inhibitor of transcription a stable RNA polymerase-template complex cannot be formed. Binding to and inactivation of RNA polymerase is reversible at high ionic strength.
mesh_terms: D002467:Cell Nucleus / Q000502:physiology*; D002854:Chromatography, Paper; D002855:Chromatography, Thin Layer; D012321:DNA-Directed RNA Polymerases / Q000037:antagonists & inhibitors*; D005994:Glycerophosphates / Q000302:isolation & purification / Q000502:physiology; D007700:Kinetics; D010804:Physarum / Q000201:enzymology*; D013698:Templates, Genetic; D014158:Transcription, Genetic
chemical_list: D005994:Glycerophosphates; D012321:DNA-Directed RNA Polymerases