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. Author manuscript; available in PMC: 2021 Nov 1.
Published in final edited form as: Trends Biochem Sci. 2020 Aug 13;45(11):923–934. doi: 10.1016/j.tibs.2020.07.004

Figure 1. Inttegrator cleavage can terminate transcription at snRNA and protein-coding genes.

Figure 1.

(A) Nascent snRNA transcripts are cleaved upstream of the 3’ box sequence (green) by the IntS11 RNA endonuclease component of the Integrator complex, which enables termination of RNA polymerase II (RNAPII) transcription. The cleaved snRNA transcript is released, further processed, and assembled into an RNA-protein complex, which includes Sm proteins (gray), that functions to catalyze pre-mRNA splicing reactions. (B) The Integrator complex can likewise be recruited to a subset of protein-coding loci. (Top) In the absence of Integrator, RNAPII transitions to productive elongation and full-length mRNAs are produced. (Bottom) When Integrator is recruited, IntS11 can cleave the nascent mRNA. This facilitates premature transcription termination and the resulting short RNAs are rapidly degraded from their 3’ ends by the RNA exosome (purple). Integrator thus blocks productive elongation and attenuates full-length mRNA production.