Matthews D J, Wells J A
Department of Protein Engineering, Genentech, Inc., South San Francisco, CA 94080, USA.
Chem Biol. 1994 Sep;1(1):25-30. doi: 10.1016/1074-5521(94)90037-x.
Human growth hormone (hGH) binds to both the hGH and human prolactin (hPRL) receptors. Binding to the hPRL receptor, however, is approximately 50-fold tighter and requires a single Zn2+ cation, unlike binding of hGH to the hGH receptor. Previous mutational studies have identified putative ligands from hGH and the hPRL receptor responsible for coordinating the interfacial Zn2+.
One of these ligands was introduced at a structurally analogous site in the extracellular domain of the hGH receptor by mutating Asn218 to His, and the resulting mutant protein showed a 20-fold increase in hGH binding in the presence of ZnCl2. Alanine-scanning mutagenesis showed that the binding site on hGH for the Asn218-->His hGH receptor in the presence of Zn2+ resembled that for the hPRL receptor.
It is possible to introduce the metal-binding site from the hPRL receptor into the homologous hGH receptor. More generally, these studies indicate that affinity between two proteins may be enhanced by design of an interfacial metal-binding site.
人生长激素（hGH）可与hGH受体和人催乳素（hPRL）受体结合。然而，与hPRL受体的结合亲和力约高50倍，且需要单个Zn2 +阳离子，这与hGH与hGH受体的结合不同。先前的突变研究已从hGH和hPRL受体中鉴定出负责配位界面Zn2 +的推定配体。
通过将Asn218突变为His，将其中一种配体引入hGH受体细胞外结构域的结构类似位点，在存在ZnCl2的情况下，所得突变蛋白的hGH结合增加了20倍。丙氨酸扫描诱变表明，在存在Zn2 +的情况下，hGH上Asn218→His hGH受体的结合位点类似于hPRL受体的结合位点。
有可能将hPRL受体的金属结合位点引入同源hGH受体。更普遍地说，这些研究表明，通过设计界面金属结合位点可以增强两种蛋白质之间的亲和力。
