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High affinity quinuclidinyl benzilate binding to rat parotid membranes requires muscarinic receptor G proteins interactions
Author(s) -
Horn Valerie J.,
Ambudkar Indu S.,
Baum Bruce J.
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)80497-q
Subject(s) - quinuclidinyl benzilate , muscarinic acetylcholine receptor , muscarinic antagonist , gtp' , chemistry , g protein , population , binding site , endocrinology , medicine , receptor , biophysics , biochemistry , biology , enzyme , environmental health
The binding of the non‐selective muscarinic antagonists [ 3 H] quinuclidinyl benzilate (QNB) to rat parotid membranes was characterized. Under equilibrium conditions. [ 3 H]QNB bound to a homogenous population of muscarinic receptors ( K d . 118±19 pM; B max 572±42 fmol/mg membrane protein. n = 12). The addition of G protein activators AIF − 4 or guanosine‐5′‐ O ‐(3‐thiotriphospate) (GTPγS) + Mg 2+ increased the K d by 77 ± 7% ( n =4. P < 0.05) and 83 ± 27% ( n =7, P < 0.05), respectively, without a change in the B max or homogeneity of the binding site. GTPγS added without exogenous Mg 2+ did not affect [ 3 H] QNB binding requires a muscarinic receptor/G protein interaction.