RNA Pol II with phosphorylated CTD: CE complex with activated GT phospho-Spt5 CE:Pol II CTD:Spt5 complex SPT5 subunit of Pol II binds the RNA triphosphatase (RTP) Authored: Buratowski, S, 2003-10-15 15:18:41 Reactome Database ID Release 4377073 Reactome, http://www.reactome.org ReactomeREACT_423 The capping enzyme interacts with the Spt5 subunit of transcription elongation factor DSIF. This interaction may couple the capping reaction with promoter escape or elongation, thereby acting as a “checkpoint” to assure that capping has occurred before the polymerase proceeds to make the rest of the transcript.