RNA Chain Elongation and Termination by Mammalian RNA Polymerase III Analysis of tRNA Gene Transcription by Imposing a Reversible Factor-mediated Block to Elongation using a Sequence-specific DNA Binding Protein

We have used a sequence-specific DNA binding protein to examine transcription elongation and termination by mammalian RNA polymerase III (polIII). The Escherichia coli lac repressor protein, bound to its cognate operator site positioned between the 3' end of the coding region and the termination site of a human tRNA gene, conditionally blocked transcription elongation by polIII in vitro in HeLa cell nuclear extracts. Arrest of elongation by …