Journal article
HEXIM2, a HEXIM1-related protein, regulates positive transcription elongation factor b through association with 7SK
The Journal of biological chemistry, Vol.280(16), pp.16360-16367
04/22/2005
DOI: 10.1074/jbc.M500424200
PMID: 15713662
Abstract
The kinase activity of positive transcription elongation factor b (P-TEFb), composed of cyclin-dependent kinase 9 and cyclin T1 or T2, is required for the transition of RNA polymerase II into productive elongation. P-TEFb activity has been shown to be negatively regulated by association with the small nuclear RNA 7SK and the HEXIM1 protein. Here, we characterize HEXIM2, a previously predicted protein with sequence similarity to HEXIM1. HEXIM2 is expressed in HeLa and Jurkat cells, and glycerol gradient analysis and immunoprecipitations indicate that HEXIM2, like HEXIM1, has a regulated association with P-TEFb. As HEXIM1 is knocked down, HEXIM2 functionally compensates for its association with P-TEFb. Electrophoretic mobility shift assays and in vitro kinase assays demonstrate that HEXIM2 forms complexes containing 7SK and P-TEFb and, in conjunction with 7SK, inhibits P-TEFb kinase activity. Our results provide strong evidence that HEXIM2 is a regulator of P-TEFb function. Furthermore, our results support the idea that the utilization of HEXIM1 or HEXIM2 to bind and inhibit P-TEFb can be differentially regulated in vivo.
Details
- Title: Subtitle
- HEXIM2, a HEXIM1-related protein, regulates positive transcription elongation factor b through association with 7SK
- Creators
- Sarah A Byers - Molecular Biology Program and Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, USAJason P PriceJeffrey J CooperQintong LiDavid H Price
- Resource Type
- Journal article
- Publication Details
- The Journal of biological chemistry, Vol.280(16), pp.16360-16367
- Publisher
- United States
- DOI
- 10.1074/jbc.M500424200
- PMID
- 15713662
- ISSN
- 0021-9258
- eISSN
- 1083-351X
- Grant note
- GM35500 / NIGMS NIH HHS
- Language
- English
- Date published
- 04/22/2005
- Academic Unit
- Biochemistry and Molecular Biology
- Record Identifier
- 9984024559302771
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