Differentiation between binding sites for angiotensin II and nonpeptide antagonists on the angiotensin II type 1 receptors.
Differentiation between binding sites for angiotensin II and nonpeptide antagonists on the angiotensin II type 1 receptors.
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血管紧张素 II 1 型受体上血管紧张素 II 和非肽拮抗剂的结合位点之间的区别。
DOI：
10.1073/pnas.91.15.7046
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发表时间：
1994
影响因子：
11.1
通讯作者：
Thue W. Schwartz
中科院分区：
文献类型：
--
作者：
H. Schambye;S. Hjorth;D. Bergsma;Ganesh M. Sathe;Thue W. Schwartz
为了表征人类血管紧张素II受体1型（AT 1受体）上的非肽类血管紧张素拮抗剂的结合位点，我们系统地交换了人类受体的片段与来自同源非洲爪蟾受体的相应片段，该受体不结合非肽类化合物。人AT 1受体跨膜片段VII的取代显著降低了所有11种测试的非肽拮抗剂的结合亲和力（55-> 2000倍），而对血管紧张素的结合没有影响。非肽类化合物的亲和力下降另外一个数量级时，跨膜段VI和连接的细胞外环3从非洲爪蟾受体也被引入到人类AT 1受体。较小的片段和跨膜段VI和VII和细胞外环3中的单个残基的交换揭示了非肽拮抗剂的结合依赖于位于跨膜段VI和VII内深处的非保守残基，特别是跨膜段VII中的Asn 295。令人惊讶的是，跨膜段VII中的所有交换，包括Asn 295到Ser取代，相对于不可逾越的拮抗剂，对竞争性拮抗剂的结合具有更显著的影响。它的结论是肽和非肽配体的结合模式上的AT 1受体是相当不同的，竞争性和不可逾越的拮抗剂大概结合重叠，但不同的网站位于跨膜段VI和VII。
To characterize binding sites for nonpeptide angiotensin antagonists on the human angiotensin II receptor type 1 (AT1 receptor) we have systematically exchanged segments of the human receptor with corresponding segments from a homologous Xenopus laevis receptor, which does not bind the nonpeptide compounds. Substitution of transmembrane segment VII of the human AT1 receptor dramatically reduced the binding affinity of all of the 11 nonpeptide antagonists tested (55- to > 2000-fold) with no effect on the binding of angiotensin. The affinity for the nonpeptide compounds decreased additionally one order of magnitude when transmembrane segment VI and the connecting extracellular loop 3 from the Xenopus receptor were also introduced into the human AT1 receptor. Exchanges of smaller segments and single residues in transmembrane segments VI and VII and extracellular loop 3 revealed that the binding of nonpeptide antagonists was dependent on nonconserved residues located deep within the transmembrane segments VI and VII, in particular Asn295 in transmembrane segment VII. Surprisingly, all exchanges in transmembrane segment VII, including the Asn295 to Ser substitution, had a more pronounced effect on the binding of the competitive antagonists relative to the insurmountable antagonists. It is concluded that the binding mode for peptide and nonpeptide ligands on the AT1 receptor is rather different and that competitive and insurmountable antagonists presumably bind to overlapping but distinct sites located in transmembrane segments VI and VII.