Fujita-Yamaguchi Y
J Biol Chem. 1984 Jan 25;259(2):1206-11.
Three insulin receptor subunits prepared from the purified receptor were isolated and characterized. Peptide mapping of the isolated subunits revealed that the Mr = 125,000 subunit (alpha) is distinct from the Mr = 90,000 subunit (beta) whereas the Mr = 50,000 subunit (beta 1) shows considerable structural homology to beta, indicating that the alpha and beta subunits are components of the intact insulin receptor. From two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the absence and presence of dithiothreitol, the purified insulin receptor was shown to be composed of heterogeneous disulfide-linked complexes of (alpha 2, 2 beta), (alpha 2, beta, beta 1), (alpha 2, 2 beta 1), (alpha 2), (alpha beta), and (alpha beta 1). The largest disulfide-linked complex (alpha 2, 2 beta) appears to be the minimum unit of the intact insulin receptor whereas the other complexes appear to be generated from (alpha 2, 2 beta) by proteolytic degradation and/or reduction. These studies provide conclusive evidence that the alpha 2 beta 2 complex is the basic structural unit of insulin receptor, as previously proposed from affinity cross-linking experiments using crude membranes by Czech's group (Czech, M. P., Massague, J., and Pilch, P. F. (1981) Trends Biochem. Sci. 6, 222-225). The biochemical approach described here should allow us to further elucidate the mechanism of insulin action.
从纯化的胰岛素受体中分离并鉴定了三个亚基。对分离出的亚基进行肽图谱分析表明，分子量为125,000的亚基（α）与分子量为90,000的亚基（β）不同，而分子量为50,000的亚基（β1）与β显示出相当大的结构同源性，这表明α和β亚基是完整胰岛素受体的组成部分。通过在有无二硫苏糖醇存在下进行的二维十二烷基硫酸钠-聚丙烯酰胺凝胶电泳，纯化的胰岛素受体显示为由（α2, 2β）、（α2, β, β1）、（α2, 2β1）、（α2）、（αβ）和（αβ1）的异质二硫键连接复合物组成。最大的二硫键连接复合物（α2, 2β）似乎是完整胰岛素受体的最小单位，而其他复合物似乎是由（α2, 2β）通过蛋白水解降解和/或还原产生的。这些研究提供了确凿的证据，证明α2β2复合物是胰岛素受体的基本结构单位，正如捷克小组之前使用粗制膜进行的亲和交联实验所提出的那样（捷克，M. P.，马萨格，J.，和皮尔希，P. F.（1981年）《生物化学趋势》6，222 - 225）。这里描述的生化方法应该使我们能够进一步阐明胰岛素作用的机制。
