Histone methyltransferase. L-lysyl-[histone] + S-adenosyl-L-methionine = H(+) + N(6)-methyl-L-lysyl-[histone] + S-adenosyl-L-homocysteine Belongs to the class V-like SAM-binding methyltransferase superfamily. Histone-lysine methyltransferase family. SET2 subfamily.