Complex sentence: Most lysine methyltransferases contain an evolutionarily conserved SET domain, which possess S-adenosylmethionine-dependent methyltransferase activity, but are structurally distinct from other S-adenosylmethionine binding proteins.
Split into simpler sentences: Most lysine methyltransferases contain an evolutionarily conserved SET domain. SET domains possess S-adenosylmethionine-dependent methyltransferase activity, but are structurally distinct from other S-adenosylmethionine binding proteins.