J Biol Chem 2002 Sep 27;27739:36061-7. doi: 10.1074/jbc.M205192200.

FCP1 phosphorylation by casein kinase 2 enhances binding to TFIIF and RNA polymerase II carboxyl-terminal domain phosphatase activity.

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Dephosphorylation of RNA polymerase II carboxyl-terminal domain (CTD) is required to resume sequential transcription cycles. FCP1 (TFIIF-dependent CTD phosphatase 1) is the only known phosphatase targeting RNAP II CTD. Here we show that in Xenopus laevis cells, xFCP1 is a phosphoprotein. On the basis of biochemical fractionation and drug sensitivity, casein kinase 2 (CK2) is shown to be the major kinase involved in xFCP1 phosphorylation in X. laevis egg extracts. CK2 phosphorylates xFCP1 mainly at a cluster of serines centered on Ser(457). CK2-dependent phosphorylation enhances 4-fold the CTD phosphatase activity of FCP1 and its binding to the RAP74 subunit of general transcription factor TFIIF. These findings unravel a new mechanism regulating CTD phosphorylation and hence class II gene transcription.

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Species referenced: Xenopus laevis
Genes referenced: csnk2b ctdp1 gtf2f1 gtf2f2