Pericentric regions form epigenetically organized, silent heterochromatin 
structures that accumulate histone H3 lysine 9 tri-methylation (H3K9me3) and 
heterochromatin protein 1 (HP1), a methylated H3K9-binding protein. At 
pericentric regions, Suv39h is the major enzyme that generates H3K9me3. Suv39h 
also interacts directly with HP1. However, the importance of HP1 interaction for 
Suv39h-mediated H3K9me3 formation at the pericentromere is not well 
characterized. To address this question, we introduced HP1 binding-defective, 
N-terminally truncated mouse Suv39h1 (ΔN) into Suv39h-deficient cells. 
Pericentric H3K9me3-positive cells were not detected by endogenous-level 
expression of ΔN. Notably, ΔN could induce pericentric accumulation of H3K9me3 
as wild type Suv39h1 did if it was overexpressed. These findings demonstrate 
that the N-terminal region of Suv39h1, presumably via HP1-Suv39h1 interaction, 
is required for Suv39h1-mediated pericentric H3K9me3 formation, but can be 
overridden if Suv39h1 is overproduced, indicating that Suv39h1-mediated 
heterochromatin formation is controlled by multiple modules, including HP1.