Molecular function

histone H4 lysine 20-specific methyltransferase activity, histone H4K20 methylation, histone lysine N-methyltransferase activity (H4-K20 specific), histone methylase activity (H4-K20 specific), histone methyltransferase activity (H4-K20 specific), histone-H4K20 methyltransferase activity

Catalysis of the reaction: S-adenosyl-L-methionine + histone H4 L-lysine (position 20) = S-adenosyl-L-homocysteine + histone H4 N6-methyl-L-lysine (position 20). This reaction is the addition of a methyl group to the lysine residue at position 20 of the histone H4 protein.

Note that in some species, the methyl group may be added to a lysine in a slightly different position of the histone H4 protein, but that this term still applies.