The highly conserved and essential protein Ssu72 has intrinsic phosphatase activity and plays an essential role in the transcription cycle. Ssu72 was originally identified in a yeast genetic screen as enhancer of a defect caused by a mutation in the transcription initiation factor TFIIB [1]. It binds to TFIIB and is also involved in mRNA elongation. Ssu72 is further involved in both poly(A) dependent and independent termination. It is a subunit of the yeast cleavage and polyadenylation factor (CPF), which is part of the machinery for mRNA 3'-end formation. Ssu72 is also essential for transcription termination of snRNAs [4][5].

1: Synthetic enhancement of a TFIIB defect by a mutation in SSU72, an essential yeast gene encoding a novel protein that affects transcription start site selection in vivo. Sun ZW, Hampsey M; Mol Cell Biol 1996;16:1557-1566. PMID:8657130

2: A role for SSU72 in balancing RNA polymerase II transcription elongation and termination. Dichtl B, Blank D, Ohnacker M, Friedlein A, Roeder D, Langen H, Keller W; Mol Cell 2002;10:1139-1150. PMID:12453421

3: Conserved and specific functions of mammalian ssu72. St-Pierre B, Liu X, Kha LC, Zhu X, Ryan O, Jiang Z, Zacksenhaus E; Nucleic Acids Res 2005;33:464-477. PMID:15659578

4: A structural perspective of CTD function. Meinhart A, Kamenski T, Hoeppner S, Baumli S, Cramer P; Genes Dev 2005;19:1401-1415. PMID:15964991

5: Ssu72 is a phosphatase essential for transcription termination of snoRNAs and specific mRNAs in yeast. Ganem C, Devaux F, Torchet C, Jacq C, Quevillon-Cheruel S, Labesse G, Facca C, Faye G; EMBO J 2003;22:1588-1598. PMID:12660165