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Updated: Aug 14, 2026

High-throughput Purification of Affinity-tagged Recombinant Proteins
Published on: August 26, 2012
Multiple interactions between RNA polymerase I, TIF-IA and TAF(I) subunits regulate preinitiation complex assembly at
Xuejun Yuan1, Jian Zhao, Hanswalter Zentgraf
1Division of Molecular Biology of the Cell II, German Cancer Research Center, D-69120 Heidelberg, Germany.
Abstract:
In mammals, growth-dependent regulation of rRNA synthesis is brought about by the transcription initiation factor TIF-IA. TIF-IA is associated with a fraction of the TBP-containing factor TIF-IB/SL1 and the initiation-competent form of RNA polymerase I (Pol I). We investigated the mechanisms that down-regulate cellular pre-rRNA synthesis and demonstrate that nutrient starvation, density arrest and protein synthesis inhibitors inactivate TIF-IA and impair the association of TIF-IA with Pol I. Moreover, we used a panel of TIF-IA deletion mutants to map the domains that mediate the interaction of TIF-IA with Pol I and TIF-IB/SL1. We found that amino acids 512-609 interact with two subunits of Pol I, RPA43 and PAF67, whereas a short, conserved motif (LARAK, amino acids 411-415) is required for the association of TIF-IA with TAF(I)95 and TAF(I)68. The results uncover an interphase for essential protein-protein interactions that facilitate Pol I preinitiation complex formation.
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