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

Figure 3

Typical distribution of histone modifications across a gene. Serine 5 phosphorylation on the RNA pol II CTD recruits Set1 to RNA pol II early in elongation, resulting in a peak of H3 K4 trimethylation near promoters [11]. Just downstream, K4 dimethylation peaks in 5′ coding regions [102, 103]. Later in elongation, serine 2 phosphorylation of the RNA pol II CTD recruits Set2, resulting in H3 K36 methylation toward the 3′ end of the coding region [60–63]. H3 K4 trimethylation recruits the NuA3 histone acetyltransferase (HAT) complex, resulting in increased H3 K14 acetylation near the promoter [104, 105]. Within the coding region, dimethylation of H3 K4 promotes the activity of the Set3 histone deacetylase complex (HDAC) [106, 107]. At the 3′ coding region, H3 K36 dimethylation promotes the activity of the Rpd3S HDAC [108–111]. Through these mechanisms, histone acetylation levels are maintained at low levels on coding regions.