A sequence of amino acids on a protein that is recognized by the oligosaccaryltransferase complex (OST) and is required for the transfer of the N-glycan precursor (Glc3Man9GlcNAc2) from the LLO to the asparagine residue as part of N-linked protein glycosylation. If an asparagine residue is not followed by an X (any amino acid except proline) and then serine or threonine, Glc3Man9GlcNAc2 will not be added to the protein by OST.