A motif of five consecutive residues and two H-bonds in which: Residue(i) is Aspartate or Asparagine (Asx), side-chain O of residue(i) is H-bonded to the main-chain NH of residue(i+2) or (i+3), main-chain CO of residue(i) is H-bonded to the main-chain NH of residue(i+3) or (i+4).