Histone-lysine N-methyltransferase SUV39H2 is a Histone methyltransferase that specifically trimethylates Lys-9 of histone H3 using monomethylated H3 Lys-9 as substrate. H3 Lys-9 trimethylation represents a specific tag for epigenetic transcriptional repression by recruiting HP1 (CBX1, CBX3 and/or CBX5) proteins to methylated histones. Mainly functions in heterochromatin regions, thereby playing a central role in the establishment of constitutive heterochromatin at pericentric and telomere regions. H3 Lys-9 trimethylation is also required to direct DNA methylation at pericentric repeats. SUV39H1 is targeted to histone H3 via its interaction with RB1 and is involved in many processes, such as cell cycle regulation, transcriptional repression and regulation of telomere length. May participate in regulation of higher-order chromatin organization during spermatogenesis. Recruited by the large PER complex to the E-box elements of the circadian target genes such as PER2 itself or PER1, contributes to the conversion of local chromatin to a heterochromatin-like repressive state through H3 Lys-9 trimethylation. Among its related pathways are Lysine degradation and Chromatin organization. Gene Ontology (GO) annotations related to this gene include chromatin binding and transcription regulatory region sequence-specific DNA binding. An important paralog of this gene is EHMT1.