The insulin receptor of embryonic chicken cartilage.
The insulin receptor of embryonic chicken cartilage.
复制标题
胚胎鸡软骨的胰岛素受体。
作者：
C. Stuart;R. Furlanetto;H. Lebovitz
用物理方法而不是酶消化法从鸡胚软骨中获得了高度纯化的质膜。证明了[125 I]碘胰岛素与这些膜的快速可逆结合。与大鼠肝脏、脂肪细胞和人单核细胞的胰岛素结合特性相似，胰岛素与软骨细胞质膜的最佳特异性结合具有明显的最佳pH值，最佳pH值为8.0，最大结合发生在2- 4 ℃。平衡结合分析显示曲线Scatchard图，其高亲和力段产生的最大亲和力为1.0 × 10（9）M-1，受体浓度为0.4 pmol/mg膜蛋白。该亲和常数与从鸡胚肝制备的膜与胰岛素结合所产生的亲和常数相似（2.5 X 10（9）M-1），大鼠肝脏（1.4 × 10（9）M-1）和小鼠肝脏（0.6 × 10（9）M ~（-1）），而受体浓度低于鸡胚肝细胞膜（1.1 pmol/mg），这反过来又低于大鼠肝膜（2.8 pmol/mg）和小鼠肝膜（3.5 pmol/mg）。动力学研究表明，增强胰岛素受体解离时，过量的胰岛素初始受体占有率低，这表明负协同性存在。除了胰岛素原和胰岛素样生长因子外，其他激素与软骨细胞胰岛素受体几乎没有相互作用。猪胰岛素原、牛胰岛素原、生长调节素C和非抑制性胰岛素样蛋白阻止[125 I]碘胰岛素与软骨细胞质膜结合，其剂量-反应曲线与未标记猪胰岛素本身平行，但相对于猪胰岛素的摩尔效价分别为15%、9%、2.5%和1.4%。猪胰岛素和胰岛素原都能阻止[125 I]碘生长调节素C与软骨细胞质膜的结合，但其摩尔效价低于未标记生长调节素C的1%。这些观察结果与鸡胚软骨中存在特异性独立胰岛素受体一致，该受体的特征与先前描述的组织中的胰岛素受体相似。胰岛素与软骨细胞生长调节素C受体的相互作用较弱。与生长调节素受体的相互作用可能是胰岛素以药理学剂量使用时对软骨发挥合成代谢作用的机制。
Highly purified plasma membranes have been obtained from embryonic chicken cartilage by physical means rather than enzymatic digestion. Rapid and reversible binding of [125I]iodoinsulin to these membranes is demonstrated. Similar to the insulin-binding properties of rat liver and adipocytes and human mononuclear cells, optimal specific binding of insulin to chondrocyte plasma membranes has a sharp pH optimum at 8.0, and maximal binding occurs at 2--4 C. Analysis of equilibrium binding reveals a curvilinear Scatchard plot, whose high affinity segment generates a maximum affinity of 1.0 X 10(9) M-1, and a receptor concentration of 0.4 pmol/mg membrane protein. This affinity constant is similar to those generated for insulin binding to membranes prepared from embryonic chicken liver (2.5 X 10(9) M-1), rat liver (1.4 X 10(9) M-1), and mouse liver (0.6 X 10(9) M-1), whereas the receptor concentration is less than that of embryonic chicken liver membranes (1.1 pmol/mg), which in turn was less than those of rat liver membranes (2.8 pmol/mg) and mouse liver membranes (3.5 pmol/mg). Kinetic studies show augmentation of insulin-receptor dissociation by excess insulin when initial receptor occupancy, is low, suggesting that negative cooperativity is present. There is little or no interaction of other hormones with the chondrocyte insulin receptor, with the exception of proinsulin and the insulin-like growth factors. Porcine proinsulin, bovine proinsulin, somatomedin C, and nonsuppressible insulin-like protein prevent [125I]iodoinsulin binding to chondrocyte plasma membranes with dose-response curves which are parallel to that of unlabeled porcine insulin itself, but with molar potencies relative to porcine insulin of 15%, 9%, 2.5%, and 1.4%, respectively. Porcine insulin and proinsulin both prevent binding of [125I]iodosomatomedin C to chondrocyte plasma membranes but with molar potencies less than 1% that of unlabeled somatomedin C. These observations are consistent with the presence of a specific independent insulin receptor in embryonic chicken cartilage which is similar in its characteristics to the insulin receptor in previously described tissues. Insulin has a weak interaction with the chondrocyte receptor for somatomedin C. Interaction with the somatomedin receptor may be the mechanism by which insulin exerts anabolic effects on cartilage when used in pharmacological amounts.