Figure 4. Model for a dual function of Suv39h1.

The two functional domains in Suv39h1 highlighting the interaction with HP1α, Ubc9 and SUMO are depicted. During de novo HP1α targeting to pericentric heterochromatin, Suv39h1 can enhance HP1α sumoylation and accelerate its recruitment. During HP1α enrichment, Suv39h1 would function as KMT leading to H3K9 trimethylation thereby providing binding sites for HP1α allowing its accumulation/retention. While the two activities are associated with distinct subdomains, they may not necessarily function in an exclusive manner and rather provide a means to integrate a metabolic sensing to the specific targeting of a nuclear domain.