Final answer:
Methylation of H3 at lysine residue 4 (K4) typically correlates with activation of gene transcription, by promoting an open chromatin structure that is accessible to transcription factors.
Step-by-step explanation:
The effect of methylation of H3 at lysine residue 4 (K4) is intricately linked to the regulation of gene transcription. This process is important in both non-dividing cells and during the interphase of dividing cells, as it involves chromatin remodeling. Methylation at H3K4 is generally associated with transcriptional activation. It facilitates the loosening of nucleosomes, thereby allowing transcription factors greater access to DNA for transcription.
Conversely, demethylation of H3K4 typically has the opposite effect, leading to transcriptional repression. It is important to note that the methylation state of histones can vary, with mono-, di-, or tri-methylation having different effects on gene expression. In particular, di-methylation of H3K4 is associated with an open chromatin structure conducive to transcription, whereas tri-methylation is strongly linked with active gene transcription.