Background：Histone methyltransferase involved in left-right axis specification in early development and mitosis. Specifically trimethylates 'Lys-9' of histone H3(H3K9me3). H3K9me3 is a specific tag for epigenetic transcriptional repression that recruits HP1(CBX1, CBX3 and/or CBX5) proteins to methylated histones. Contributes to H3K9me3 in both the interspersed repetitive elements and centromere-associated repeats. Plays a role in chromosome condensation and segregation during mitosis.
