Catalysis of the reaction: L-lysyl4- + S-adenosyl-L-methionine = H+ + N6-methyl-L-lysyl4- + S-adenosyl-L-homocysteine. This reaction is the addition of a single methyl group to the unmethylated lysine residue at position 4 of histone H3, producing histone H3K4me.
histone H4-K4 methylation