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A toxin from the green mamba Dendroaspis angusticeps : Amino acid sequence and selectivity for muscarinic m4 receptors
Author(s) -
Jolkkonen Mikael,
van Giersbergen Paul L.M.,
Hellman Ulf,
Wernstedt Christer,
Karlsson Evert
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)00933-3
Subject(s) - selectivity , chemistry , muscarinic acetylcholine receptor , toxin , biochemistry , receptor , catalysis
Muscarinic toxin 3 (MT3) (65 amino acids, four disulphides, M r 7379) was isolated from the venom of the African snake Dendroaspis angusticeps (green mamba) and its amino acid sequence determined. Its ability to inhibit the binding of [ 3 H] N ‐methylscopolamine ([ 3 H]NMS) to Chinese hamster ovary cells stably expressing subtypes of muscarinic receptors was studied. MT3 displayed high affinity for the m4 receptor (p K i = 8.7 ± 0.06), 40‐fold lower affinity at m1 receptors (p K i = 7.11 ± 0.17) whereas no inhibition of [ 3 H]NMS binding to m2, m3 and m5 receptors was observed at concentrations up to 1 μM. This makes MT3 the most selective m4 receptor ligand known to date.