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. Author manuscript; available in PMC: 2019 Jul 22.
Published in final edited form as: Wiley Interdiscip Rev RNA. 2019 Mar 7;10(4):e1529. doi: 10.1002/wrna.1529

Figure 4: Kinetic competition between RNAPII and Sen1/Xrn2.

Figure 4:

The rate of transcription varies, due to factors that influence RNAPII kinetics and passage through chromatin, and these variations in rate can affect the termination window. In general, it is thought that slower elongation rates promote earlier termination, while faster elongation rates lead to termination spreading further downstream. The faster RNAPII moves along a gene, the harder it will be for the termination machinery to catch up, and how long it takes for RNAPII to be caught will help determine what termination pathway is used. Two termination-associated proteins thought to be tasked with catching RNAPII are Xrn2 (also known as Rat1) and Sen1 (yeast homolog of Senataxin). Pausing of RNAPII would promote termination via either Xrn2 or Sen1 by providing the ability for them to catch up to the elongation complex (Mischo, 2013).