Reconstitution of functional muscarinic receptors by co-expression of amino- and carboxyl-terminal receptor fragments

FEBS Lett. 1993 Mar 15;319(1-2):195-200. doi: 10.1016/0014-5793(93)80066-4.


Truncated m2 and m3 muscarinic receptors (referred to as m2- and m3-trunc), containing transmembrane domains I-V and the N-terminal portion of the third cytoplasmic loop, were co-expressed in COS-7 cells with the corresponding C-terminal receptor fragments (referred to as m2- and m3-tail; containing transmembrane domains VI and VII). Expression of any of these four polypeptides alone did not result in any detectable [3H]N-methylscopolamine ([3H]NMS) binding activity. However, specific [3H]NMS binding sites were observed after co-expression of m2-trunc with m2-tail and m3-trunc with m3-tail. These sites displayed ligand binding properties similar to those of the two wild-type receptors. The 'reconstituted' m3-trunc/m3-tail receptor was also able to stimulate agonist-dependent phosphatidyl inositol hydrolysis in a fashion similar to the wild-type m3 receptor, whereas all other polypeptide combinations were inactive. These data suggest that muscarinic receptors are assembled in a fashion analogous to two-subunit receptors.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Line
  • Gene Expression
  • Humans
  • Molecular Sequence Data
  • N-Methylscopolamine
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism*
  • Phosphatidylinositols / metabolism
  • Plasmids
  • Protein Conformation
  • Rats
  • Receptors, Muscarinic / genetics
  • Receptors, Muscarinic / metabolism*
  • Scopolamine Derivatives / metabolism
  • Transfection


  • Peptide Fragments
  • Phosphatidylinositols
  • Receptors, Muscarinic
  • Scopolamine Derivatives
  • N-Methylscopolamine