Liapakis G, Thermos K
Department of Basic Sciences, School of Health Sciences, University of Crete, Heraklion, Greece.
Neuropeptides. 1992 Jan;21(1):13-9. doi: 10.1016/0143-4179(92)90148-p.
We have identified specific receptors for somatostatin (SS) in the rabbit retina using the radioligand [125I]Tyr11-Somatostatin. [125I]Tyr11-SS bound with high affinity to retinal membranes as was ascertained by both kinetic and saturation experiments. Scatchard analysis of the saturation data for [125I]Tyr11-SS binding to retinal membranes suggest a single population of sites with an apparent affinity constant (KD) of 0.90 +/- 0.20 nM and a maximum number of binding sites (Bmax) of 104 +/- 52 fmol/mg protein. The specific binding of [125I]Tyr11-SS was displaced in a dose-dependent manner by SS, Tyr11-SS, SMS 201-995, SS-28 and D-Trp8-SS. The inactive SS analog SS28(1-14) as well as the peptides CRF and bombesin had no effect. In addition, the specific binding of [125I]Tyr11-SS was attenuated by GTPgS. These findings demonstrate the presence of a selective receptor for SS in the rabbit retina that is coupled to guanine nucleotide binding protein(s).
我们使用放射性配体[125I]Tyr11-生长抑素在兔视网膜中鉴定出生长抑素（SS）的特异性受体。动力学和饱和实验均证实，[125I]Tyr11-SS与视网膜膜具有高亲和力结合。对[125I]Tyr11-SS与视网膜膜结合的饱和数据进行Scatchard分析表明，存在单一的位点群体，其表观亲和常数（KD）为0.90±0.20 nM，最大结合位点数（Bmax）为104±52 fmol/mg蛋白质。[125I]Tyr11-SS的特异性结合被SS、Tyr11-SS、SMS 201-995、SS-28和D-Trp8-SS以剂量依赖性方式取代。无活性的SS类似物SS28(1-14)以及肽促肾上腺皮质激素释放因子（CRF）和蛙皮素均无作用。此外，[125I]Tyr11-SS的特异性结合被GTPγS减弱。这些发现证明兔视网膜中存在与鸟嘌呤核苷酸结合蛋白偶联的SS选择性受体。
