Wilson D S, Tappel A L
Department of Food Science and Technology, University of California, Davis 95616.
J Inorg Biochem. 1993 Sep;51(4):707-14. doi: 10.1016/0162-0134(93)85003-q.
Competitive binding assays were performed to determine the amount of binding of 75Se-labeled plasma selenoprotein P (PSP) to membranes from different rat tissues at physiologic pH. 75Se PSP for use as a ligand in the binding assays was labeled in vivo by injecting rats with 75Se selenious acid. PSP was obtained from plasma by salt precipitation and affinity and ion-exchange chromatography. Membranes for receptor assays were prepared from liver, kidney, testes, and brain of rats fed diets with either 0.01, 0.1, or 2 ppm selenium. At pH 7.4 PSP was bound differentially to tissues in the following order: brain > kidney > testes > liver. Specific binding of PSP to tissue membranes from rats fed the different levels of selenium increased with increasing amounts of dietary selenium. Saturation assays indicated apparent saturation of membrane receptors by the 75Se-labeled PSP. Another significant new finding was a 134-kDa complex of PSP and membrane receptor, identified by gel-filtration chromatography of cross-linked samples from binding assays. This provides evidence for a membrane receptor for PSP in rat tissues.
进行竞争性结合试验以确定在生理pH值下，75Se标记的血浆硒蛋白P（PSP）与来自不同大鼠组织的膜的结合量。用作结合试验中配体的75Se PSP通过给大鼠注射75Se亚硒酸在体内进行标记。通过盐沉淀、亲和色谱和离子交换色谱从血浆中获得PSP。受体试验用的膜取自喂食含0.01、0.1或2 ppm硒饲料的大鼠的肝脏、肾脏、睾丸和大脑。在pH 7.4时，PSP与组织的结合存在差异，顺序如下：脑＞肾＞睾丸＞肝脏。随着日粮硒含量的增加，PSP与喂食不同硒水平大鼠的组织膜的特异性结合增加。饱和试验表明，75Se标记的PSP使膜受体出现明显饱和。另一个重要的新发现是，通过对结合试验交联样品进行凝胶过滤色谱分析，鉴定出一种134 kDa的PSP与膜受体复合物。这为大鼠组织中存在PSP的膜受体提供了证据。
