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Two‐step binding of green mamba toxin to muscarinic acetylcholine receptor
Author(s) -
Toomela T.,
Jolkkonen M.,
Rinken A.,
Järv J.,
Karlsson E.
Publication year - 1994
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(94)00926-0
Subject(s) - muscarinic acetylcholine receptor , toxin , antagonist , agonist , chemistry , muscarinic acetylcholine receptor m2 , competitive antagonist , muscarinic acetylcholine receptor m1 , muscarinic acetylcholine receptor m5 , pharmacology , mechanism of action , muscarinic acetylcholine receptor m3 , receptor , acetylcholine receptor , biochemistry , biology , in vitro
The mechanism of binding of toxin MT2 from venom of green mamba Dendroaspis angusticeps to muscarinic acetylcholine receptors from rat cerebral cortex was investigated by studying the kinetics of the toxin—receptor interaction. The muscarinic antagonist N ‐methyl‐[ 3 H]scopolamine was used as a ‘reporter’ ligand. Evidence for a mechanism of toxin—receptor interaction comprising at least two steps was obtained. Such a mechanism increases the potency of the toxin. The first step was fast with no competition between the toxin and the antagonist. The second step was slow with formation of a more stable toxin—receptor complex and inhibition of the antagonist binding. It is proposed that the snake toxin is a muscarinic agonist of slow action.