Interplay between 7SK snRNA and oppositely charged regions in HEXIM1 direct the inhibition of P-TEFb.

ABSTRACT: Transcription elongation of eukaryotic genes by RNA polymerase II depends on the positive transcription elongation factor b (P-TEFb). When sequestered into the large complex, P-TEFb kinase activity is inhibited by the coordinate actions of 7SK small nuclear RNA (7SK snRNA) and hexamethylene bisacetamide (HMBA)-induced protein 1 (HEXIM1). We found that the basic region in HEXIM1 directs its nuclear import via two monopartite and two bipartite nuclear localization sequences. Moreover, the arginine-rich motif within it is essential for its binding to 7SK snRNA, P-TEFb, and inhibition of transcription. Notably, the basic region interacts with the adjacent acidic regions in the absence of RNA. The removal of the positive or negative charges from these regions in HEXIM1 leads to its sequestratio

SUBMITTER: Barboric M 

PROVIDER: S-EPMC1356324 | biostudies-literature | 2005 Dec

REPOSITORIES: biostudies-literature