The functional role of the binding site aspartate in muscarinic acetylcholine receptors, probed by site-directed mutagenesis

Eur J Pharmacol. 1995 May 26;289(3):429-37. doi: 10.1016/0922-4106(95)90151-5.


Mutation of the Asp in transmembrane domain three of the muscarinic receptors to Asn (M1) or Glu (M1 and M2) strongly reduced the high-affinity component of agonist binding, and the M1 phosphoinositide response. Formation of the acetylcholine-receptor binary complex was also strongly inhibited. In contrast, binary complex formation by other agonists, as well as the antagonist (-)-N-methylscopolamine, was less affected. Ionic bonding between the carboxylate oxyanion and the positively-charged headgroup probably anchors acetylcholine when it is bound in its active conformation, but alternative, non-productive, binding modes, promoted by non-polar forces, may contribute to binary complex formation by other ligands.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcholine / analogs & derivatives
  • Acetylcholine / pharmacology
  • Animals
  • Aspartic Acid / metabolism*
  • Binding Sites
  • CHO Cells
  • Cloning, Molecular
  • Cricetinae
  • GTP-Binding Proteins / metabolism
  • Glutamic Acid / metabolism
  • Ligands
  • Muscarinic Agonists / metabolism
  • Mutagenesis, Site-Directed*
  • Phosphatidylinositols / metabolism
  • Receptors, Muscarinic / biosynthesis
  • Receptors, Muscarinic / genetics
  • Receptors, Muscarinic / metabolism*


  • Ligands
  • Muscarinic Agonists
  • Phosphatidylinositols
  • Receptors, Muscarinic
  • Aspartic Acid
  • Glutamic Acid
  • GTP-Binding Proteins
  • Acetylcholine