Allosteric interaction of dynorphin and myelin basic protein with muscarinic receptors.

Interaction of the basic peptides dynorphin A and myelin basic protein with muscarinic receptors was investigated in rat heart and cerebral cortex using radioligand receptor binding assays. Results showed that these peptides inhibit the binding of the muscarinic ligand [3H]N-methylscopolamine at equilibrium and alter the kinetics of ligand dissociation in an allosteric fashion. The number of basic amino acid residues in the composition of dynorphin A is important in eliciting its allosteric interactions. Our data suggest that endogenous basic peptides play a role in regulating the conformation of muscarinic receptors.