Figure 1.

A model for the kinetics of methylation of chromatin-bound transcription factors by histonemodifying lysine methyltransferases. (A) The transcription factor (TF) and the methyltransferases are free from DNA. (B) The TF binds to its site. (C) The methyltransferases are recruited. (D) The methyltransferases are activated and catalyze methylations of both histones and the TF. Alternatively, some methyltransferases may be pre-associated with some promoters before the TF arrives. Trimethylation of TFs is uncommon, in contrast to the frequent trimethylation of histones. This figure is adapted from Lu and Stark ⁵⁶.