Functional analysis of MOR-1 splice variants of the mouse mu opioid receptor gene Oprm
Functional analysis of MOR-1 splice variants of the mouse mu opioid receptor gene Oprm
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DOI：
10.1002/syn.10277
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发表时间：
2004-01-01
期刊：
影响因子：
2.3
通讯作者：
Pasternak, GW
中科院分区：
文献类型：
--
作者：
Bolan, EA;Pan, YX;Pasternak, GW
据报道，一系列 mu 阿片受体基因 Oprm 剪接变体仅在 C 末端不同。这些变体都包含该基因的外显子 1、2 和 3，这些外显子负责编码所有七个跨膜结构域。尽管 MOR-1 还具有在 C 末端编码额外 12 个氨基酸的外显子 4，但由于选择性剪接，其他 MOR-1 变体具有与 MOR-1 中的氨基酸序列不同的独特氨基酸序列。所有这些变体在结合测定中都是μ选择性的。当前的研究探讨了这些变体刺激 [S-35]GTPgammaS 结合的能力，以评估它们的功能。只有 mu 阿片类药物刺激 [S-35]GTPgammaS 结合。在 mu 阿片类药物中，我们注意到克隆之间的最大刺激存在显着差异。这对于 β-内啡肽最为突出，它在 MOR-1E 表达细胞中刺激 [S-35]GTRgammaS 结合的程度比 [D-Ala(2)、MePhe(4)、Gly(ol)(5)]脑啡肽 (DAMGO；130%) 更大，但在 MOR-1C 细胞中的效果远低于 DAMGO (44%)。药物最大刺激的排名顺序在克隆之间也有所不同。强啡肽 A、β-内啡肽和吗啡在刺激 MOR-1E 中的 [S-35]GTPgammaS 结合方面最有效，而 M6G 和芬太尼在 MOR-1 表达细胞中最有效。一些药物的效力 (EC50) 在克隆之间也存在很大差异，药物刺激 [S-35]GTPgammaS 结合的效力与其结合亲和力之间的相关性较差。总之，这些发现揭示了变体之间显着的功能差异，这些差异只能通过它们 C 末端的结构差异来解释。 Synapse 51:11-18, 2004。(C) 2003 Wiley-Liss, Inc.
A series of mu opioid receptor gene Oprm splice variants have been reported that differ only at their C-terminus. These variants all contain exons 1, 2, and 3 of the gene, the exons responsible for coding all seven transmembrane domains. Whereas MOR-1 also has exon 4 that encodes for an additional 12 amino acids at the tip of the C-terminus, the other MOR-1 variants have unique amino acid sequences distinct from those in MOR-1 due to alternative splicing. All these variants are mu-selective in binding assays. The current study explored the ability of these variants to stimulate [S-35]GTPgammaS binding to assess them functionally. Only mu opioids stimulated [S-35]GTPgammaS binding. Among the mu opioids we noted marked differences in their maximal stimulation among the clones. This was most prominent with beta-endorphin, which stimulated [S-35]GTRgammaS binding in the MOR-1E expressing cells to a greater degree than [D-Ala(2),MePhe(4),Gly(ol)(5)]enkephalin (DAMGO; 130%) and was far less effective than DAMGO in MOR-1C cells (44%). The rank order of maximal stimulation of the drugs varied among the clones as well. Dynorphin A, beta-endorphin and morphine were most effective in stimulating [S-35]GTPgammaS binding in MOR-1E, while M6G and fentanyl were most effective in MOR-1 expressing cells. The potency (EC50) of some of the drugs also varied extensively among the clones, with a poor correlation between the potency of the drugs to stimulate [S-35]GTPgammaS binding and their binding affinity. Together, these findings reveal marked functional differences among the variants that only can be explained by their structural differences at the tip of their C-terminus. Synapse 51:11-18, 2004. (C) 2003 Wiley-Liss, Inc.