Laugwitz K L, Offermanns S, Spicher K, Schultz G
Institut für Pharmakologie, Freie Universität Berlin, Germany.
Neuron. 1993 Feb;10(2):233-42. doi: 10.1016/0896-6273(93)90314-h.
Opioids are regarded to act via receptors interacting with heterotrimeric pertussis toxin (PTX)-sensitive G proteins. In membranes of SH-SY5Y cells, the mu-selective agonist [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin (DAGO) and the delta-selective agonist [D-Pen2,Pen5]-enkephalin (DPDPE) stimulated incorporation of the photoreactive GTP analog [alpha-32P]GTP azidoanilide into proteins comigrating with the alpha subunits of G(i1), G(i2), G(i3), G(o1), and another form of G(o), presumably G(o2). In membranes of PTX-treated cells, both agonists were ineffective. Subtype-specific immunoprecipitation of G protein alpha subunits photolabeled in the absence or presence of agonists revealed profound differences between mu and delta opioid receptors in coupling to PTX-sensitive G proteins. Whereas activated delta opioid receptors preferentially coupled to G(i1), activated mu opioid receptors more effectively coupled to G(i3). Additionally, we provide evidence that G(o) subtypes are also differentially activated by the two receptors. Thus, mu and delta opioid receptors appear to discriminate between PTX-sensitive G proteins and lead to activation of distinct G protein subtypes.
阿片类药物被认为是通过与异三聚体百日咳毒素（PTX）敏感的G蛋白相互作用的受体来发挥作用。在SH-SY5Y细胞的膜中，μ选择性激动剂[D-Ala2，N-Me-Phe4，Gly5-ol]-脑啡肽（DAGO）和δ选择性激动剂[D-Pen2，Pen5]-脑啡肽（DPDPE）刺激了光反应性GTP类似物[α-32P]GTP叠氮苯胺掺入与G（i1）、G（i2）、G（i3）、G（o1）以及另一种形式的G（o）（可能是G（o2））的α亚基共迁移的蛋白质中。在PTX处理的细胞的膜中，两种激动剂均无效。在不存在或存在激动剂的情况下对光标记的G蛋白α亚基进行亚型特异性免疫沉淀，揭示了μ和δ阿片受体在与PTX敏感的G蛋白偶联方面存在显著差异。活化的δ阿片受体优先与G（i1）偶联，而活化的μ阿片受体更有效地与G（i3）偶联。此外，我们提供证据表明G（o）亚型也被这两种受体差异激活。因此，μ和δ阿片受体似乎能够区分PTX敏感的G蛋白，并导致不同G蛋白亚型的激活。
