Negative cooperativity in binding of muscarinic receptor agonists and GDP as a measure of agonist efficacy.

ABSTRACT:

Background and purpose

Conventional determination of agonist efficacy at G-protein coupled receptors is measured by stimulation of guanosine-5'-γ-thiotriphosphate (GTPγS) binding. We analysed the role of guanosine diphosphate (GDP) in the process of activation of the M₂ muscarinic acetylcholine receptor and provide evidence that negative cooperativity between agonist and GDP binding is an alternative measure of agonist efficacy.

Experimental approach

Filtration and scintillation proximity assays measured equilibrium binding as well as binding kinetics of [³⁵S]GTPγS and [³H]GDP to a mixture of G-proteins as well as individual classes of G-proteins upon binding of structurally different agonists to the M₂ muscarinic acetylcholine receptor.

Key results

Agonists displayed

SUBMITTER: Jakubik J 

PROVIDER: S-EPMC3051377 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature