Guanine nucleotide-induced positive cooperativity in muscarinic-cholinergic antagonist binding

Biochem Biophys Res Commun. 1986 Jan 14;134(1):172-7. doi: 10.1016/0006-291x(86)90543-7.


The effect of guanine nucleotides on the binding of [3H] Quinuclidinyl benzilate to heart muscarinic receptors was studied. It was observed that GTP and Gpp (NH)p increased antagonist binding. Scatchard transformation of the data resulted in curvilinear plots (downward concavity) consistent with positive cooperativity. Graphic analysis for cooperativity indicated that guanine nucleotides: a) increased slightly but consistently the affinity for the antagonist (independent of receptor occupancy) and b) induce positive cooperativity in the binding of [3H]QNB (dependent of receptor occupancy).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Atropine / pharmacology
  • Guanosine Triphosphate / analogs & derivatives*
  • Guanosine Triphosphate / pharmacology
  • Guanylyl Imidodiphosphate / pharmacology*
  • Kinetics
  • Male
  • Myocardium / metabolism
  • Quinuclidinyl Benzilate / metabolism
  • Rats
  • Rats, Inbred Strains
  • Receptors, Cholinergic / metabolism*
  • Receptors, Muscarinic / metabolism*


  • Receptors, Cholinergic
  • Receptors, Muscarinic
  • Guanylyl Imidodiphosphate
  • Quinuclidinyl Benzilate
  • Atropine
  • Guanosine Triphosphate