Histone methyltransferase that trimethylates histone H3 'Lys-36' forming H3K36me3. Involved in transcription elongation as well as in transcription repression. The methyltransferase activity requires the recruitment to the RNA polymerase II, which is CTK1 dependent. L-lysyl(36)-[histone H3] + 3 S-adenosyl-L-methionine = 3 H(+) + N(6),N(6),N(6)-trimethyl-L-lysyl(36)-[histone H3] + 3 S-adenosyl-L-homocysteine Interacts with the RNA polymerase II hyperphosphorylated CTD. Interacts with CYC8. The AWS and SET domains are necessary for transcription repression. Present with 217 molecules/cell in log phase SD medium. Belongs to the class V-like SAM-binding methyltransferase superfamily. Histone-lysine methyltransferase family. SET2 subfamily.