Fig. (1).

Epigenetic regulation of protein-coding genes in trypanosomatids. Schematic representation of a hypothetical chromosome that contains four PTUs, showing the distribution of the epigenetic marks involved in transcription regulation. Transcription of the first and second PTUs (left part of the figure) is divergent, whereas transcription of the third and four PTUs (right part of the figure) is convergent. Nucleosomes located at the vicinity of transcription initiation regions (labelled with arrows) contain histone variants H2A.Z and H2B.V [17]. Histones H3 in such nucleosomes are acetylated at K9/K14 and tri-methylated at K4, while histones H4 are acetylated at K10 [17, 73]. The bromodomain factor BDF3 also binds at transcription initiation regions [17]. Transcription termination regions show enrichment of histone variants H3.V and H4.V [17] and base J [63, 64]. The relative position of nucleosomes along PTUs [78] is indicated at the top of the figure.