Related Experiment Video
Updated: Aug 6, 2026

Chromatin Isolation by RNA Purification (ChIRP)
Published on: March 25, 2012
Polyadenylation of RNA in vitro in isolated chromatin and nuclei
Abstract:
Poly(A) is added post-transcriptionally to RNA transcribed in vitro by endogenous form B DNA-dependent RNA polymerase bound to the template in isolated nuclei or chromatin. It is also added to processed fragments of the products from alpha-amanitin-resistant RNA polymerases A and/or C. The poly(A) segments are of similar size to those found in nuclear RNA pulse-labelled in vivo and are added onto the 3' terminus of RNA chains (whether pre-existing, completed during the incubation in vitro or created by fragmentation of larger RNA transcripts). That poly(A) addition is not directly mediated by any of the nuclear DNA-dependent RNA polymerases is shown by the differential sensitivities of RNA and poly(A) syntheses to increasing ionic strength and transcriptional inhibitors such as the exotoxin from Bacillus thuringiensis.
Related Concept Videos
pre-mRNA Processing
Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a “cap” to the 5’ end of the growing transcript. In this process, a 5’ phosphate is replaced by modified guanosine that has a methyl group attached to it (7-Methyl guanosine). This 5’ cap helps the...
RNA Stability
Eukaryotic RNA Polymerases
All three eukaryotic RNAPs require specific transcription factors, of which the...
Chromatin Structure Regulates pre-mRNA Processing
The chromatin structure, especially...
Transcription Initiation
The promoters and enhancers and their accessory proteins allow tight regulation of...
Pre-mRNA Processing: Modification of pre-mRNA Ends
Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a cap to the 5' end of the growing transcript. In this process, a 5' phosphate is replaced by modified guanosine that has a methyl group attached (7-methyl guanosine). This 5' cap helps the cell...

