What is pseudo-templated transcription? Pseudo-templated transcription describes a process that results in the production of a homopolymeric stretch of RNA directed by a shorter stretch (usually 3-7) of complementary nucleotides on the template (either RNA or DNA). The effects of pseudo-templated transcription are very diverse. In some cases, strictly homopolymeric RNAs are made; in others, pseudo-templated nucleotides are added at either the 5' or 3' ends of otherwise normally templated

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... ipts; and finally, sometimes pseudo-templated nucleotides are inserted at a specific internal site during elongation within an otherwise normally templated RNA. As a result, pseudo-templated transcription is involved in events such as transcriptional frameshifting (programmed or not) and synthesis of the poly(A) head or poly(A) tail of various mRNAs. We will try to describe the general features of pseudo-templated transcription and assess its importance within a more general framework. Reiterative copying of a template was first described by Chamberlin and Berg (1964, and references therein). They observed production of polyadenylic acid in an in vitro system where denatured natural DNA or oligo(T) is provided as a template and ATP, the sole substrate for the Escherichia coli RNA polymerase holoenzyme (RNAP). With denatured DNA, production of poly(A) was inhibited by low concentration of the other three NTPs and was proposed to be directed by a stretch of Ts on the DNA template strand. With oligo(T) as template, the resulting poly(A) exceeded the length of the template by as much as 20-fold. Similar examples were reported at this time, suggesting that under certain conditions RNAP had the ability to direct slippage during RNA synthesis (for review, see Yager and Von Hippel 1987, and references therein). Downloaded from 10.1101/gad.5.5.707 Access the most recent version at doi: 5: 1991, Genes Dev. J P Jacques and D Kolakofsky organisms. Pseudo-templated transcription in prokaryotic and eukaryotic References http://genesdev.cshlp.org/content/5/5/707.full.html#ref-list-1