The Roles of the Paf1 Complex and Associated Histone Modifications in Regulating Gene Expression

Figure 2

The Paf1C promotes histone H2B monoubiquitylation and histone H3 K4, K36, and K79 methylation. In yeast, the ubiquitin conjugating enzyme, Rad6, and the ubiquitin ligase, Bre1, monoubiquitylate H2B K123 [179–181]. H2B monoubiquitylation is a prerequisite for di- and trimethylation of H3 K4 and K79 by the histone methyltransferases Set1 and Dot1, respectively [71, 80, 182, 183]. Histone H3 is methylated on K36 by the methyltransferase Set2 [184]. Paf1 and Rtf1 subunits of the Paf1C are required for H2B K123 monoubiquitylation and the downstream di- and trimethylation of H3 K4 and K79 [9–12]. Paf1 and Ctr9 are required for trimethylation of K36 on histone H3 [8].