Site-directed mutagenesis of the rat beta1-adrenoceptor. Involvement of Tyr356 (7.43) in (+/-)cyanopindolol but not (+/-)[125Iodo]cyanopindolol binding

Eur J Med Chem. 2004 Jul;39(7):625-31. doi: 10.1016/j.ejmech.2004.03.009.


To determine the role played by Tyr(356 (7.43)) in the rat beta(1)-adrenoceptor in binding the antagonists (+/-)cyanopindolol (4-[3-(t-butylamino]-3-(2'-cyano-indoloxy)-2-propanolol) and its iodinated analogue (+/-)[(125)Iodo]cyanopindolol (1-(t-butylamino]-3-(2'-cyano-3'-iodo-indoloxy)-2-propanolol), Tyr(356 (7.43)) was mutated to either Phe or Ala and binding affinities determined for wild type and mutant rat beta(1)-adrenoceptors. Our results indicate that Tyr(356 (7.43)) is important for (+/-)cyanopindolol, but not (+/-)[(125)Iodo]cyanopindolol, binding and that (+/-)cyanopindolol adopts a "reverse" binding orientation whereas (+/-)[(125)Iodo]cyanopindolol cannot be accommodated in this binding mode. We define a "reverse" antagonist binding mode as one where the aryloxy moiety interacts with residues on transmembrane helices 1, 2, 3 and 7. The beta(1)-adrenoceptor site-directed mutagenesis results are the first to support a "reverse" antagonist binding orientation and the involvement of Tyr(356 (7.43)) in this binding mode.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic beta-Antagonists / chemistry
  • Adrenergic beta-Antagonists / metabolism*
  • Adrenergic beta-Antagonists / pharmacology
  • Animals
  • Iodine Radioisotopes
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • Pindolol / analogs & derivatives*
  • Pindolol / chemistry
  • Pindolol / metabolism*
  • Pindolol / pharmacology
  • Protein Binding
  • Protein Conformation
  • Radioligand Assay
  • Rats
  • Receptors, Adrenergic, beta-1 / genetics
  • Receptors, Adrenergic, beta-1 / metabolism*
  • Tyrosine / chemistry
  • Tyrosine / genetics
  • Tyrosine / metabolism*


  • Adrenergic beta-Antagonists
  • Iodine Radioisotopes
  • Receptors, Adrenergic, beta-1
  • Tyrosine
  • cyanopindolol
  • Pindolol