Molecular function

histone H3 lysine 4-specific methyltransferase activity, histone H3K4 methylase activity, histone lysine N-methyltransferase activity (H3-K4 specific), histone methylase activity (H3-K4 specific), histone methyltransferase activity (H3-K4 specific), histone-H3K4 methyltransferase activity

Catalysis of the reaction: S-adenosyl-L-methionine + histone H3 L-lysine (position 4) = S-adenosyl-L-homocysteine + histone H3 N6-methyl-L-lysine (position 4). This reaction is the addition of up to three methyl groups to the lysine residue at position 4 of the histone H3 protein.

Note that in some species, the methyl group may be added to a lysine in a slightly different position of the histone H3 protein, but that this term still applies.