Role of the His273 located in the sixth transmembrane domain of the angiotensin II receptor subtype AT2 in ligand-receptor interaction.
Role of the His273 located in the sixth transmembrane domain of the angiotensin II receptor subtype AT2 in ligand-receptor interaction.
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位于血管紧张素 II 受体亚型 AT2 第六跨膜结构域的 His273 在配体-受体相互作用中的作用。
DOI：
10.1006/bbrc.1999.0207
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Pulakat,L
中科院分区：
文献类型：
--
作者：
Turner,CA;Cooper,S;Pulakat,L
血管紧张素II受体亚型AT 1和AT 2是具有七个跨膜结构域（TMD）拓扑结构的蛋白质，并且共享34%的同源性。结果表明，His 256，位于第六TMD的AT 1受体，是需要激动剂激活的Phe 8侧链的血管紧张素II，虽然取代这个残基与精氨酸或谷氨酰胺没有显着改变的亲和力结合的受体。我们推测位于AT 2受体第六跨膜区的His 273可能在AT 2受体的功能中发挥类似的作用，尽管该残基在最初的同源性比较中未被鉴定为保守残基。因此，我们用精氨酸或谷氨酰胺取代了AT 2受体的His 273，并以异种卵母细胞为表达系统分析了突变受体的配体结合特性。我们的研究结果表明，AT 2受体突变体His 273 Arg和His 273 Glu已经失去了对[125 I-Sar 1-Ile 8]Ang II的亲和力，[125 I-Sar 1-Ile 8] Ang II是一种结合AT 1和AT 2受体的肽配体，125 I-CGP 42112 A是一种特异性结合AT 2受体的肽配体。因此，His 273位于第六TMD的AT 2受体似乎发挥了重要作用，在确定该受体的结合特性。此外，这些结果沿着我们先前的观察，即位于AT 2受体的第5 TMD的Lys 215对于其与[125 I-Sar 1-Ile 8]Ang II的高亲和力结合是必需的，表明位于AT 2受体的第5和第6 TMD的关键氨基酸对于AT 2与其配体的高亲和力结合是必需的。
Angiotensin II receptor subtypes AT1 and AT2 are proteins with seven transmembrane domain (TMD) topology and share 34% homology. It was shown that His256, located in the sixth TMD of the AT1 receptor, is needed for the agonist activation by the Phe8 side chain of angiotensin II, although replacing this residue with arginine or glutamine did not significantly alter the affinity binding of the receptor. We hypothesized that the His273 located in the sixth transmembrane domain of the AT2 receptor may play a similar role in the functions of the AT2 receptor, although this residue was not identified as a conserved residue in the initial homology comparisions. Therefore, we replaced His273 of the AT2 receptor with arginine or glutamine and analyzed the ligand-binding properties of the mutant receptors usingXenopusoocytes as an expression system. Our results suggested that the AT2 receptor mutants His273Arg and His273 Glu have lost their affinity to [125I-Sar1-Ile8]Ang II, a peptidic ligand that binds both the AT1 and AT2 receptors and to125I-CGP42112A, a peptidic ligand that binds specifically to the AT2 receptor. Thus, His273 located in the sixth TMD of the AT2 receptor seems to play an important role in determining the binding properties of this receptor. Moreover, these results along with our previous observation that the Lys215 located in the 5th TMD of the AT2 receptor is essential for its high affinity binding to [125I-Sar1-Ile8]Ang II indicate that key amino acids located in the 5th and 6th TMDs of the AT2 receptor are needed for high affinity binding of the AT2 to its ligands.