Histone-lysine N-methyltransferase SETD1B (SETD1B)

Histone methyltransferase that specifically methylates'Lys-4' of histone H3, when part of the SET1 histone methyltransferase (HMT) complicated, but not if the neighboring'Lys- 9' residue is already methylated. H3 'Lys-4' methylation represents a specific tag for epigenetic transcriptional activation.

The non-overlapping localization with SETD1A suggests that SETD1A and SETD1B make non-redundant contributions to the epigenetic control of chromatin structure and gene expression. Specifically tri-methylates 'Lys-4' of histone H3 in vitro.