Skip to main content
. Author manuscript; available in PMC: 2013 Jan 6.
Published in final edited form as: Cell. 2012 Jul 6;150(1):53–64. doi: 10.1016/j.cell.2012.05.029

Figure 7. A proposed model of co-transcriptional PCPA and its suppression by U1.

Figure 7

Cleavage and polyadenylation factors (CPSF) associate with pol II TEC and is thus poised for 3′-end cleavage and polyadenylation, but can also cause premature termination (PCPA) from cryptic PASs found throughout pre-mRNAs. U1 is recruited to nascent transcripts by multiple interactions, including base pairing of its 5′-end with cognate pre-mRNA sequences (5’ ss and other) and can suppress PCPA by inhibiting the pol II associated CPSF over < 1kb range. U1 shortage increases the probability of distal PASs remaining unprotected.