Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

We have used EM visualization of active genes on plasmid vectors in Xenopus oocyte nuclei to investigate the relationship between poly(A) signals and RNA polymerase II transcription termination. Although a functional poly(A) signal is required for efficient termination, cotranscriptional RNA cleavage at the poly(A) site is not. Furthermore, the phenomena of termination and cotranscriptional RNA cleavage can be uncoupled, and the efficiency of both varies independently on different copies of the same plasmid template in the same oocyte nucleus. The combined observations are consistent with a scenario in which there is template-specific addition to Pol II (presumably at the promoter) of elongation and/or RNA processing factors, which are altered upon passage through a poly(A) signal, resulting in termination and, in some cases, cotranscriptional RNA cleavage.


Journal article


Mol Cell

Publication Date





379 - 387


Animals, DNA-Binding Proteins, Genes, Microscopy, Electron, Oocytes, Plasmids, Poly A, Promoter Regions, Genetic, RNA Polymerase II, RNA, Messenger, Response Elements, Templates, Genetic, Transcription Factor TFIIIA, Transcription Factors, Transcription, Genetic, Xenopus laevis