Transcriptional activity of positive transcription elongation factor b kinase in vivo requires the C-terminal domain of RNA polymerase II.

摘要: Phosphorylation of the carboxyl-terminal domain (CTD) RNA polymerase II (RNAPII) is an important step in transcription and positive elongation factor b (P-TEFb) has been proposed to facilitate at many genes. The P-TEFb contains a catalytic subunit (Cdk9) that, association with cyclin (cyclinT1), ability phosphorylate CTD substrate vitro. Here, we demonstrate that cyclinT1/Cdk9-mediated requires CTD-containing RNAPII, suggesting major target cyclinT1/Cdk9 complex vivo. Unlike Cdk7 Cdk8, two other cyclin-dependent kinases are capable phosphorylating vitro, found only Cdk9 activates gene expression catalysis-dependent manner. Finally, unlike cyclinT1 T2, targeted recruitment promoter DNA cyclinK (a recently described alternative partner Cdk9) does not stimulate Collectively, our data strongly indicate kinase subunits cyclinT/Cdk9 specifically involved RNAPII functional this