Updated project metadata. Human methytransferase like proteins (METTL) are part of a large protein family characterized by the presence of binding domains for S-adenosyl methionine, a co-substrate in most methylation reactions. Despite the fact that members of this protein family were shown or predicted to be DNA, RNA or protein methyltransferases, most METTL proteins are still poorly characterized. Identification of the complexes in which these potential enzymes act could help to understand their function(s) and substrate specificities. Here we systematically studied interacting partners of METTL protein family members using label-free quantitative mass spectrometry.