A conserved motif for the transport of G protein-coupled receptors from the endoplasmic reticulum to the cell surface
A conserved motif for the transport of G protein-coupled receptors from the endoplasmic reticulum to the cell surface
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DOI：
10.1074/jbc.m313881200
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发表时间：
2004-07-16
影响因子：
4.8
通讯作者：
Wu, GY
中科院分区：
文献类型：
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作者：
Duvernay, MT;Zhou, FG;Wu, GY
G 蛋白偶联受体输出运输的结构决定因素尚不清楚。在本报告中，我们确定了 α(2B)-肾上腺素能受体 (AR) 和血管紧张素 II 1A 型受体 (AT1R) 的羧基末端 (CT) 在从内质网 (ER) 转运至细胞表面的过程中的作用。缺乏CT的α(2B)-AR和AT1R突变体完全无法转运到细胞表面并被困在ER中。丙氨酸扫描诱变揭示CT中的残基Phe(436)和Ile(443)-Leu(444)是α(2B)-AR输出所必需的。 Phe（436）和Ile（443）-Leu（444）之间的插入或缺失以及Ile（443）-Leu（444）突变为FF严重破坏了α（2B）-AR运输，表明存在明确的空间要求，这对于它们作为调节ER受体运输的单一基序的功能至关重要。此外，羧基末端截短的突变体以及 Phe(436) 和 Ile(443)-Leu(444) 突变体无法结合配体，并且 alpha(2B)-AR CT 以 Phe(436)-Ile(443)-Leu(444) 依赖性方式将其转运特性赋予没有 CT 的 AT1R 突变体。这些数据表明 Phe436 和 Ile(443)-Leu(444) 可能参与受体 ER 的正确折叠和输出。同样，CT 中的残基 Phe(309) 和 Leu(316)-Leu(317) 被确定为 AT1R 输出所必需的。序列 F(X)(6)LL（其中 X 可以是任何残基，L 是亮氨酸或异亮氨酸）在许多 G 蛋白偶联受体的近膜 CT 中高度保守，并且可能作为介导从 ER 到细胞表面的受体转运的常见基序发挥作用。
The structural determinants for the export trafficking of G protein-coupled receptors are poorly defined. In this report, we determined the role of carboxyl termini (CTs) of alpha(2B)-adrenergic receptor (AR) and angiotensin II type 1A receptor (AT1R) in their transport from the endoplasmic reticulum (ER) to the cell surface. The alpha(2B)-AR and AT1R mutants lacking the CTs were completely unable to transport to the cell surface and were trapped in the ER. Alanine-scanning mutagenesis revealed that residues Phe(436) and Ile(443)-Leu(444) in the CT were required for alpha(2B)-AR export. Insertion or deletion between Phe(436) and Ile(443)-Leu(444) as well as Ile(443)-Leu(444) mutation to FF severely disrupted alpha(2B)-AR transport, indicating there is a defined spatial requirement, which is essential for their function as a single motif regulating receptor transport from the ER. Furthermore, the carboxyl-terminally truncated as well as Phe(436) and Ile(443)-Leu(444) mutants were unable to bind ligand and the alpha(2B)-AR CT conferred its transport properties to the AT1R mutant without the CT in a Phe(436)- Ile(443)-Leu(444)-dependent manner. These data suggest that the Phe436 and Ile(443)-Leu(444) may be involved in both proper folding and export from the ER of the receptor. Similarly, residues Phe(309) and Leu(316)-Leu(317) in the CT were identified as essential for AT1R export. The sequence F(X)(6)LL (where X can be any residue, and L is leucine or isoleucine) is highly conserved in the membrane-proximal CTs of many G protein-coupled receptors and may function as a common motif mediating receptor transport from the ER to the cell surface.