van Koppen C J, Sokolovsky M
Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel.
Biochem Biophys Res Commun. 1988 Mar 30;151(3):1069-73. doi: 10.1016/s0006-291x(88)80474-1.
Chemical modification of muscarinic M1 receptors in a synaptoneurosomal preparation of rat cerebral cortex by a hydrophilic histidyl-group-specific reagent, diethylpyrocarbonate (DEP), reduces the number of [3H]-4NMPB binding sites in a dose-dependent way. The effect can be reversed by hydroxylamine treatment. No such effect is observed when carbethoxylation with 2.5 mM DEP is carried out in the presence of atropine, 4NMPB, pirenzepine or carbachol. These findings indicate that DEP specifically modifies histidyl residue(s) positioned at the binding site in members of the M1 receptor family. However, treatment with 2.5 mM DEP in the presence of various muscarinic ligands significantly disturbs the binding state of agonists. The results suggest that M1 receptors may have more than one histidyl residue of importance in ligand binding.
在大鼠大脑皮层的突触体神经小体标本中，亲水性组氨酸特异性试剂焦碳酸二乙酯（DEP）对毒蕈碱型M1受体进行化学修饰，会以剂量依赖的方式减少[3H]-4NMPB结合位点的数量。该效应可通过羟胺处理逆转。当在阿托品、4NMPB、哌仑西平或卡巴胆碱存在的情况下用2.5 mM DEP进行乙氧羰基化时，未观察到这种效应。这些发现表明，DEP特异性修饰位于M1受体家族成员结合位点的组氨酸残基。然而，在各种毒蕈碱配体存在的情况下用2.5 mM DEP处理会显著干扰激动剂的结合状态。结果表明，M1受体在配体结合中可能有多个重要的组氨酸残基。
