The Structural and Functional Role of the B-chain C-terminal Arginine in the Relaxin-3 Peptide Antagonist, R3(BΔ23-27)R/I5
The Structural and Functional Role of the B-chain C-terminal Arginine in the Relaxin-3 Peptide Antagonist, R3(BΔ23-27)R/I5
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DOI：
10.1111/j.1747-0285.2008.00756.x
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发表时间：
2009-01-01
影响因子：
3
通讯作者：
Wade, John D.
中科院分区：
文献类型：
--
作者：
Hossain, Mohammed Akhter;Bathgate, Ross A. D.;Wade, John D.
松弛素-3是胰岛素超家族的成员，参与调节应激和摄食行为。它在大脑中高度表达，是受体RXFP 3的内源性配体。由于松弛素-3也与松弛素受体RXFP 1相互作用，因此选择性激动剂和拮抗剂对于研究松弛素-3/RXFP 3对的生理功能至关重要。类似物R3（B Delta 23-27）R/I5，其中C-末端截短的人松弛素-3（H3）B-链与INSL 5 A-链结合，是一种有效的选择性RXFP 3拮抗剂，并且由于重组蛋白生产过程，在B-链C-末端保留有Arg残基。为了研究该残基在RXFP 3受体结合和活化中的作用，化学组装含有B链C末端Arg的类似物R3（B Delta 23 - 27）R/I5和R3（B Delta 23-27）R以及均缺乏Arg的R3（B Delta 23-27）/I5和R3（B Delta 23-27），并评估它们的二级结构和受体活性。这些肽通常具有相似的构象，但具有额外Arg残基的肽显示出对RXFP 3的亲和力显著增加。有趣的是，与R3（B Delta 23-27）R和R3（B Delta 23-27）R/I5相反，肽R3（B Delta 23-27）是弱激动剂。这表明C-末端Arg虽然增加了亲和力，但改变了肽与受体结合的方式，从而阻止了活化，使R3（B Delta 23-27）R/I5具有有效的拮抗活性。
Relaxin-3, a member of the insulin superfamily, is involved in regulating stress and feeding behavior. It is highly expressed in the brain and is the endogenous ligand for the receptor RXFP3. As relaxin-3 also interacts with the relaxin receptor RXFP1, selective agonists and antagonists are crucial for studying the physiological function(s) of the relaxin-3/RXFP3 pair. The analog R3(B Delta 23-27)R/I5, in which a C-terminally truncated human relaxin-3 (H3) B-chain is combined with the INSL5 A-chain, is a potent selective RXFP3 antagonist and has an Arg residue remaining on the B-chain C-terminus as a consequence of the recombinant protein production process. To investigate the role of this residue in the RXFP3 receptor binding and activation, the analogs R3(B Delta 23-27)R/I5 and R3(B Delta 23-27)R containing the B-chain C-terminal Arg as well as R3(B Delta 23-27)/I5 and R3(B Delta 23-27), both lacking the Arg, were chemically assembled and their secondary structure and receptor activity assessed. The peptides generally had a similar conformation but those with the extra Arg residue displayed a significantly increased affinity for the RXFP3. Interestingly, in contrast to R3(B Delta 23-27)R and R3(B Delta 23-27)R/I5, the peptide R3(B Delta 23-27) is a weak agonist. This suggests that the C-terminal Arg, although increasing the affinity, alters the manner in which the peptide binds to the receptor and thereby prevents activation, giving R3(B Delta 23-27)R/I5 its potent antagonistic activity.