Recent structural and mechanistic insights into post-translational enzymatic glycosylation

► New 3D structural insights have revealed the action of key mammalian O-glycosyltransferases and N-glycosyltransferases. ► N-glycosylation may involve amide 'twisiting' to active the nucleophile. ► New compounds harness unusual mechanisms to inhibit O-GlcNAc transferases. ► Protein fucosylation unveiled in PoFUT1 and PoFUT2. ► SNi mechanisms are placed on a firmer experimental foundation.