Transcription Elongation Factor A1 (TCEA1)

Transcription elongation factors help RNA polymerase II to transcribe past blockages due to specific DNA sequences, DNA-binding proteins, and transcription-arresting drugs. Transcription elongation factors in humans fall into 2 classes: the SIII /TF2F class, members of which increase the average rate of RNA chain elongation ; and the SII class, which releases RNA polymerase II from transcriptional arrest . In the presence of SII, a protein that stimulates the nuclease activity, pol II quantitatively removed misincorporated nucleotides from the nascent transcript during rapid chain extension. The basis of discrimination between the correct and incorrect base was the slow addition of the next nucleotide to the mismatched terminus.