Cyclin-dependent kinase 9–cyclin T2 complex (CDK9/cyclin T2)

The CDK9/cyclin T2 complex is a heterodimer formed by cyclin-dependent kinase 9 (CDK9) and cyclin T2 (encoded by the CCNT2 gene), together constituting an essential part of the positive transcription elongation factor b (P-TEFb) enzyme complex. P-TEFb phosphorylates the C-terminal domain (CTD) of RNA polymerase II, promoting transcriptional elongation and regulating expression of many key genes. Either cyclin T1 or cyclin T2 can partner with CDK9 to confer full kinase activity. The CDK9/cyclin T2 complex specifically plays roles in cell cycle progression, myogenesis, and responses to differentiation signals. Dysregulated P-TEFb activity is implicated in cancer, viral replication (notably HIV), and muscle pathologies. The complex is therapeutically targeted by small-molecule CDK inhibitors in oncology and has been considered in anti-HIV strategies.

Other names

CDK9–cyclin T2P-TEFb (Positive Transcription Elongation Factor b - when referring to the active kinase complex containing CDK9 and either cyclin T1 or T2)CCNT2 (Cyclin T2)CDK9

Inhibition of kinase activity, resulting in suppression of transcriptional elongation; Arresting cell cycle progression; Induction of apoptosis through transcriptional repression (especially in rapidly proliferating target cells); Inhibition of viral transcription (notably HIV by blocking Tat-mediated effects)