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Updated: Aug 1, 2026
An Oligonucleotide-based Tandem RNA Isolation Procedure to Recover Eukaryotic mRNA-Protein Complexes
Published on: August 18, 2018
Isolation and characterization of polyadenylation complexes assembled in vitro
K L Veraldi1, G Edwalds-Gilbert, C C MacDonald
1Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pennsylvania 15261, USA.
Abstract:
We developed a two-step purification of mammalian polyadenylation complexes assembled in vitro. Biotinylated pre-mRNAs containing viral or immunoglobulin poly(A) sites were incubated with nuclear extracts prepared from mouse myeloma cells under conditions permissive for in vitro cleavage and polyadenylation and the mixture was fractionated by gel filtration; complexes containing biotinylated pre-mRNA and bound proteins were affinity purified on avidin-agarose resin. Western analysis of known components of the polyadenylation complex demonstrated copurification of polyadenylation factors with poly(A) site-containing RNA but not with control RNA substrates containing either no polyadenylation signals or a point mutation of the AAUAAA polyadenylation signal. Polyadenylation complexes that were assembled on exogenous RNA eluted from the Sephacryl column in fractions consistent with their size range extending from 2 to 4 x 10(6) Mr. Complexes endogenous to the extract were of approximately the same apparent size, but more heterogeneous in distribution. This method can be used to study polyadenylation/cleavage complexes that may form upon a number of different RNA sequences, an important step towards defining which factors might differentially associate with specific RNAs.
Insights
Researchers purified mammalian polyadenylation complexes using a novel two-step method. This technique isolates RNA-protein complexes involved in polyadenylation, aiding the study of gene expression regulation.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Polyadenylation is a crucial post-transcriptional modification in eukaryotes.
- Understanding the protein complexes involved in polyadenylation is essential for deciphering gene regulation.
Purpose of the Study:
- To develop and validate a two-step purification method for mammalian polyadenylation complexes.
- To enable the study of polyadenylation complexes associated with specific RNA sequences.
Main Methods:
- In vitro assembly of polyadenylation complexes using biotinylated pre-mRNAs and mouse myeloma nuclear extracts.
- Fractionation by gel filtration followed by affinity purification on avidin-agarose resin.
- Western blot analysis to identify copurified polyadenylation factors.
Main Results:
- Successful purification of polyadenylation complexes containing specific RNA substrates.
- Demonstrated copurification of known polyadenylation factors with functional poly(A) sites.
- Characterized the size of both in vitro assembled and endogenous polyadenylation complexes.
Conclusions:
- The developed method effectively isolates functional polyadenylation complexes.
- This technique allows for the investigation of RNA-protein interactions within these complexes.
- Facilitates future studies on sequence-specific RNA binding by polyadenylation factors.
