H3K9 methylation enhances HP1-associated epigenetic silencing complex assembly and suppresses off-chromatin binding.

happen in the complex and crowded environment of the nucleus. Using single-molecule tracking of HP1 proteins and their binding partners, we identified the rules that govern their complex formation in the native chromatin context, and we found that chromatin- previously thought to be an inert platform-enhances complex formation between HP1 and its binding partners.