Catalysis of the reaction: L-lysyl4-[histone H3] + 3 S-adenosyl-L-methionine = 2 H+ + N6,N6-trimethyl-L-lysyl4-[histone H3] + 3 S-adenosyl-L-homocysteine. This reaction is the successive addition of three methyl groups to the unmethylated lysine residue at position 4 of histone H3, producing histone H3K4me3.
Source:RHEA:60260,
PMID:18375658