Role of the third intracellular loop of the Angiotensin II receptor subtype AT2 in ligand-receptor interaction
Role of the third intracellular loop of the Angiotensin II receptor subtype AT2 in ligand-receptor interaction
复制标题
DOI：
10.1016/s0014-5793(99)00085-x
复制
发表时间：
1999-02-19
期刊：
影响因子：
3.5
通讯作者：
Pulakat, L
中科院分区：
文献类型：
--
作者：
Dittus, J;Cooper, S;Pulakat, L
血管紧张素Ⅱ（AngII）受体亚型AT 1和AT 2占34%;为阐明第三胞内环（3rd ICL）在决定AT_1和AT_2受体功能异同中的作用，我们产生了一种嵌合受体，其中AT 2受体的第三个IOL被AT 1受体的第三个IOL取代。通过在非洲爪蟾卵母细胞中表达该受体来测定该受体的配体结合特性和信号传导特性。使用[I-125-Sar（1）-Ile（8）] Ang II（一种结合AT 1和AT 2受体亚型的肽配体）和I-125-CGP 42112 A（一种对AT 2受体特异的肽配体）的配体结合研究，然而，表达嵌合受体的卵母细胞的IP 3水平与表达AT 1受体的卵母细胞的IP 3水平相当，表明嵌合受体可以响应于Ang II而偶联至磷脂酶C途径，我们先前已经表明，位于AT 2受体第五跨膜结构域（TMD）中的位置215中存在的氨基酸的性质在决定其对不同配体的亲和力中起重要作用，我们对配体的检测结果-嵌合受体的结合研究进一步支持了这样的想法，即跨越第五TMD和第三ICL的区域的结构组织是嵌合受体结合的基础。AT 2受体在决定该受体的配体结合特性方面具有重要作用。(C)1999年欧洲生物化学学会联合会。
Angiotensin II (Ang II) receptor subtypes AT1 and AT2 share 34%;, overall homology, but the least homology is in their third intracellular loop (3rd ICL), In an attempt to elucidate the role of the 3rd ICL in determining the similarities and differences in the functions of the AT1 and the AT2 receptors, we generated a chimeric receptor in which the 3rd IOL of the AT2 receptor was replaced with that of the AT1 receptor. Ligand-binding properties and signaling properties of this receptor were assayed by expressing this receptor in Xenopus oocytes, Ligand-binding studies using [I-125-Sar(1)-Ile(8)] Ang II, a peptidic ligand that binds both the AT1 and the AT2 receptor subtypes, and I-125-CGP42112A, a peptidic ligand that is specific for the AT2 receptor, showed that the chimeric receptor has lost affinity to both ligands, However, IP3 levels of the oocytes expressing the chimeric receptor were comparable to the IP3 levels of the oocytes expressing the AT1 receptor, suggesting that the chimeric receptors could couple to phospholipase C pathway in response to Ang II, We have shown previously that the nature of the amino acid present in the position 215 located in the fifth transmembrane domain (TMD) of the AT2 receptor plays an important role in determining its affinity to different ligands, Our results from the ligand-binding studies of the chimeric receptor further support the idea that the structural organization of the region spanning the 5th TMD and the 3rd ICL of the AT2 receptor has an important role in determining the ligand-binding properties of this receptor. (C) 1999 Federation of European Biochemical Societies.