Histone methyltransferase that catalyzes methyl group transfer from S-adenosyl-L-methionine to the epsilon-amino group of 'Lys-4' of histone H3 (H3K4) . Part of chromatin remodeling machinery predominantly forms H3K4me1 methylation marks at active chromatin sites where transcription and DNA repair take place (, ). Acts as a coactivator for estrogen receptor by being recruited by ESR1, thereby activating transcription .
Subcellular locations: Nucleus
Expressed in most adult tissues, including a variety of hematoipoietic cells, with the exception of the liver.