Baxter R C, Williams P F
Biochem Biophys Res Commun. 1983 Oct 14;116(1):62-7. doi: 10.1016/0006-291x(83)90380-7.
In contrast to its stimulation of insulin binding to human placental membranes, calcium inhibited the binding of insulin-like growth factor-I. The effects on receptors for both peptides were half-maximal at 2 mM calcium, and were entirely due to alterations in high affinity binding sites for the respective ligands. Calcium decreased the affinity of insulin-like growth factor-I sites, while stimulating the expression of high affinity insulin sites. Competition by each peptide at the receptor for the other peptide was enhanced by calcium. Modulation by calcium might provide a mechanism to amplify functional differences between the two structurally similar receptors.
与钙刺激胰岛素与人胎盘膜结合相反，钙抑制胰岛素样生长因子-I的结合。对这两种肽受体的作用在2 mM钙浓度时达到半数最大效应，且完全是由于各自配体的高亲和力结合位点发生改变。钙降低了胰岛素样生长因子-I位点的亲和力，同时刺激了高亲和力胰岛素位点的表达。钙增强了每种肽在受体上对另一种肽的竞争。钙的调节作用可能提供一种机制来放大这两种结构相似受体之间的功能差异。
