Fig. 1.

CpG methylation and regulation of gene expression. Unmethylated or hypomethylated DNA (usually in the promoter region) allows binding of the transcription factors (TF) and other regulatory mechanisms which results in transcription and mRNA production. Methylated DNA (bottom panel) obstructs binding of the TF, and in some cases might recruit methyl-CpG binding proteins and other transcription co-repressors, blocking access of the transcription enzymes and resulting in gene silencing.