P-TEFb

Patent Granted The positive transcription elongation factor, P-TEFb, plays an essential role in the regulation of transcription by RNA polymerase II (Pol II) in eukaryotes.[1] Immediately following initiation Pol II becomes trapped in promoter proximal paused positions on the majority of human genes (Figure 1).[2][3] P-TEFb is a cyclin dependent kinase that can phosphorylate the DRB sensitivity inducing factor (DSIF)[4] and negative elongation factor (NELF),[5] as well as the carboxyl terminal domain of the large subunit of Pol II[6] and this causes the transition into productive elongation leading to the synthesis of mRNAs.