Gether U, Johansen T E, Snider R M, Lowe J A, Nakanishi S, Schwartz T W
University Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark.
Nature. 1993 Mar 25;362(6418):345-8. doi: 10.1038/362345a0.
Non-peptide ligands for peptide receptors have been discovered in several systems through file screening programs, but the mechanism of action for these candidate drugs is obscure as they do not chemically resemble the native peptides. The compound CP 96345 is a high-affinity, non-peptide antagonist of the substance P (NK1) receptor, which is important in pain perception and neurogenic inflammation. Here we identify epitopes on the NK1 receptor responsible for the specific binding of CP 96345 by systematic exchange of corresponding segments between the NK1 receptor and the homologous NK3 (neurokinin B) receptor, which does not bind the non-peptide ligand. Non-conserved residues, in two epitopes around the top of transmembrane segment V and in one epitope at the top of transmembrane segment VI, are essential for the specific action of CP 96345 on the NK1 receptor, but are surprisingly not important for the binding of the natural peptide ligand, substance P. Susceptibility to the non-peptide antagonists can be conveyed to the previously unresponsive NK3 receptor by mutational transfer of this discontinuous epitope from the NK1 receptor.
通过文献筛选程序，在多个系统中发现了肽受体的非肽配体，但这些候选药物的作用机制尚不清楚，因为它们在化学结构上与天然肽不同。化合物CP 96345是P物质（NK1）受体的高亲和力非肽拮抗剂，该受体在痛觉和神经源性炎症中起重要作用。在这里，我们通过系统交换NK1受体和同源NK3（神经激肽B）受体之间的相应片段，确定了NK1受体上负责CP 96345特异性结合的表位，NK3受体不结合该非肽配体。跨膜片段V顶部周围的两个表位和跨膜片段VI顶部的一个表位中的非保守残基，对于CP 96345对NK1受体的特异性作用至关重要，但令人惊讶的是，对于天然肽配体P物质的结合并不重要。通过从NK1受体进行这种不连续表位的突变转移，可以将对非肽拮抗剂的敏感性传递给先前无反应的NK3受体。
