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Updated: Aug 13, 2026

High-throughput Purification of Affinity-tagged Recombinant Proteins
Published on: August 26, 2012
RNA contacts the two large polymerase subunits and a 52-kDa polypeptide in nucleolar RNA polymerase I transcribing
1Department of Biological Chemistry, School of Medicine, University of California, Davis 95616.
Abstract:
The interactions between nascent RNA and RNA polymerase I-transcribing complexes were studied by photoaffinity labeling in HeLa nucleoli. Specific labeling of enzyme subunits Ia, Ib, and of a 52-kDa polypeptide was observed. The 52-kDa polypeptide was shown to be associated with the transcribing complex by immunoprecipitation with RNA polymerase I antibodies and by glycerol gradient centrifugation. Transcripts that were kept short by inclusion of a chain-terminating nucleotide or with short incubation times contacted mainly subunits Ia and Ib. Decreasing chain terminator concentration or increasing incubation time resulted in additional labeling of the 52-kDa polypeptide. These data indicate that the 52-kDa polypeptide contacts nascent RNA after it has left the Ia-Ib domain.
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