Protein-lysine N-methyltransferase. Monomethylates 'Lys-310' of the RELA subunit of NF-kappa-B complex, leading to down-regulation of NF-kappa-B transcription factor activity (PubMed:21131967, PubMed:30189201, PubMed:21515635). Monomethylates 'Lys-8' of H2AZ (H2AZK8me1) (PubMed:23324626). Required for the maintenance of embryonic stem cell self-renewal (By similarity). Methylates PAK4. L-lysyl-[protein] + S-adenosyl-L-methionine = H(+) + N(6)-methyl-L-lysyl-[protein] + S-adenosyl-L-homocysteine L-lysyl(8)-[histone H2AZ] + S-adenosyl-L-methionine = H(+) + N(6)-methyl-L-lysyl(8)-[histone H2AZ] + S-adenosyl-L-homocysteine Activated by automethylation. Optimum pH is 10. Monomer, homodimer and homotrimer; these structures are stabilized in the presence of S-adenosyl-L-methionine (SAM). Automethylated; Lys-39 and Lys-179 serve as the major automethylation sites. Belongs to the class V-like SAM-binding methyltransferase superfamily. Histone-lysine methyltransferase family. SETD6 subfamily.