English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The positive transcription elongation factor b (P-TEFb) regulates RNA polymerase II elongation. In cells, P-TEFb partitions between small active and larger inactive states. In the latter, HEXIM1 binds to 7SK snRNA and recruits as well as inactivates P-TEFb in the 7SK snRNP. Several stimuli can affect this P-TEFb equilibrium. In this study, we demonstrate that protein kinase C (PKC) phosphorylates the serine at position158 (S158) in HEXIM1. This phosphorylated HEXIM1 protein neither binds to 7SK snRNA nor inhibits P-TEFb. Phorbol esters or the engagement of the T cell antigen receptor, which activate PKC and the expression of the constitutively active (CA) PKCθ protein, which is found in T cells, inhibit the formation of the 7SK snRNP. All these stimuli increase P-TEFb-dependent transcription. In contrast, the kinase-negative PKCθ and the mutant HEXIM1 (S158A) proteins block effects of these PKC-activating stimuli. These results indicate that the phosphorylation of HEXIM1 by PKC represents a major regulatory step of P-TEFb activity in cells.

PKC phosphorylates HEXIM1 and regulates P-TEFb activity