绿曼巴蛇（Dendroaspis angusticeps）的一种毒素：氨基酸序列及对毒蕈碱型m4受体的选择性
A toxin from the green mamba Dendroaspis angusticeps: amino acid sequence and selectivity for muscarinic m4 receptors.
作者信息
Jolkkonen M, van Giersbergen P L, Hellman U, Wernstedt C, Karlsson E
机构信息
Department of Biochemistry, Biomedical Centre, Uppsala, Sweden.
出版信息
FEBS Lett. 1994 Sep 19;352(1):91-4. doi: 10.1016/0014-5793(94)00933-3.
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 [3H]N-methylscopolamine ([3H]NMS) to Chinese hamster ovary cells stably expressing subtypes of muscarinic receptors was studied. MT3 displayed high affinity for the m4 receptor (pKi = 8.7 +/- 0.06), 40-fold lower affinity at ml receptors (pKi = 7.11 +/- 0.17) whereas no inhibition of [3H]NMS binding to m2, m3 and m5 receptors was observed at concentrations up to 1 microM. This makes MT3 the most selective m4 receptor ligand known to date.
毒蕈碱毒素3（MT3）（65个氨基酸，4个二硫键，相对分子质量7379）是从非洲绿曼巴蛇（Dendroaspis angusticeps）的毒液中分离出来的，并测定了其氨基酸序列。研究了它抑制[3H]N-甲基东莨菪碱（[3H]NMS）与稳定表达毒蕈碱受体亚型的中国仓鼠卵巢细胞结合的能力。MT3对m4受体表现出高亲和力（pKi = 8.7±0.06），对m1受体的亲和力低40倍（pKi = 7.11±0.17），而在浓度高达1微摩尔时未观察到对[3H]NMS与m2、m3和m5受体结合的抑制作用。这使得MT3成为迄今为止已知的最具选择性的m4受体配体。
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