The N-terminal tail of histone H3 can be extensively modified, and depending on the number, location, and combination of these modifications, these changes may promote the formation of heterochromatin. What is the result of heterochromatin formation

Repression of gene expression  

Explanation:

Heterochromatin is formed by highly-packed DNA regions. A functional consequence of heterochromatin formation is that these regions become inaccessible to transcription factors, thereby inhibiting gene transcription (genes in these regions are 'switched off'). Heterochromatin is formed by epigenetic modifications added to histone tails that form nucleosomes, i.e., histones H2A, H2B, H3 and H4. The epigenetic marks include, among others, acetylation and methylation.

cell regulation is conducted by special proteins.

yes? sounds right, but you didn’t ask a question.