Membranes of neuron-like NG108-15 hybrid cells bind [3H]quinuclidinyl benzilate (QNB) with high affinity and specificity. Greater than 90% of total [3H]QNB binding is to sites having the pharmacological specificity of muscarinic acetylcholine receptors. Three significant features characterize the interaction of ligands with these sites: (1) Specific binding of [3H]QNB at equilibrium follows a simple adsorption isotherm with an apparent KD of 1 × 10-10 M; (2) Rates of [3H]QNB association and dissociation are biphasic and, as the binding reaction proceeds, the fraction of readily dissociable [3H]QNB decreases; (3) Competition against [3H]QNB for specific binding sites by antagonists gives a slope of 1 when analyzed on Hill plots, but competition for binding sites by agonists gives a slope of less than 1. A simple two-step model for activation is proposed to account for these features.
|Original language||English (US)|
|Number of pages||9|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Apr 29 1980|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology