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Updated: Aug 6, 2025

Polysome Fractionation and Analysis of Mammalian Translatomes on a Genome-wide Scale
Published on: May 17, 2014
RNA Pol II preferentially regulates ribosomal protein expression by trapping disassociated subunits
Yuanjun Li1, Jie Huang1, Lijun Bao1
1Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.
Abstract:
RNA polymerase II (RNA Pol II) has been recognized as a passively regulated multi-subunit holoenzyme. However, the extent to which RNA Pol II subunits might be important beyond the RNA Pol II complex remains unclear. Here, fractions containing disassociated RPB3 (dRPB3) were identified by size exclusion chromatography in various cells. Through a unique strategy, i.e., "specific degradation of disassociated subunits (SDDS)," we demonstrated that dRPB3 functions as a regulatory component of RNA Pol II to enable the preferential control of 3' end processing of ribosomal protein genes directly through its N-terminal domain. Machine learning analysis of large-scale genomic features revealed that the little elongation complex (LEC) helps to specialize the functions of dRPB3. Mechanistically, dRPB3 facilitates CBC-PCF11 axis activity to increase the efficiency of 3' end processing. Furthermore, RPB3 is dynamically regulated during development and diseases. These findings suggest that RNA Pol II gains specific regulatory functions by trapping disassociated subunits in mammalian cells.
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