O94992

HEXIM1(HEXIM P-TEFb complex subunit 1) is a protein that is upregulated upon treatment with the differentiating agent hexamethylene bisacetamide. HEXIM1 plays a crucial role in regulating transcription by inhibiting the positive transcription elongation factor b (P-TEFb) complex, which is essential for the elongation phase of RNA polymerase II-mediated transcription. This inhibition occurs through HEXIM1′s association with the 7SK small nuclear ribonucleic acid particle, which is vital for maintaining proper gene expression levels. The P-TEFb complex, composed of the catalytic subunit Cdk9 and regulatory subunits Cyclin T1 or T2, is pivotal in controlling eukaryotic gene expression, and HEXIM1′s ability to modulate this complex underscores its importance in cellular processes. HEXIM1 and its homolog HEXIM2 can form stable homo- and hetero-oligomers, which may facilitate the assembly of the 7SK ribonucleoprotein complex, further emphasizing HEXIM1′s significance in transcriptional regulation.