Serine/threonine-protein phosphatase 2A catalytic subunit alpha isoform
RNA polymerase II CTD heptapeptide repeat S7 phosphatase activity
Identification of Integrator-PP2A complex (INTAC), an RNA polymerase II phosphatase.
The 14-subunit metazoan-specific Integrator contains an endonuclease that cleaves nascent RNA transcripts. Here, we identified a complex containing Integrator and protein phosphatase 2A core enzyme (PP2A-AC), termed INTAC. The 3.5-angstrom-resolution structure reveals that nine human Integrator subunits and PP2A-AC assemble into a cruciform-shaped central scaffold formed by the backbone and shoulder modules, with the phosphatase and endonuclease modules flanking the opposite sides. As a noncanonical PP2A holoenzyme, the INTAC complex dephosphorylates the carboxy-terminal repeat domain of RNA polymerase II at serine-2, -5, and -7 and thus regulates transcription. Our study extends the function of PP2A to transcriptional regulation and reveals how dual enzymatic activities-RNA cleavage and RNA polymerase II dephosphorylation-are structurally and functionally integrated into the INTAC complex.