Ultrastructural localization of insulin receptors on adipocytes.
Ultrastructural localization of insulin receptors on adipocytes.
复制标题
脂肪细胞上胰岛素受体的超微结构定位。
DOI：
--
复制
发表时间：
1975
影响因子：
11.1
通讯作者：
R. Smith
中科院分区：
文献类型：
--
作者：
L. Jarett;R. Smith
制备稳定的、生物活性的、共价连接的铁蛋白-胰岛素复合物的方法已经被修改，与原始方法相比，产量增加了25倍，同时铁蛋白与胰岛素的摩尔比从40:1降低到1:1。对分离脂肪细胞的超微结构研究显示，铁蛋白-胰岛素以不规则簇状与糖萼包被相关的细胞表面特异性结合。观察到的铁蛋白-胰岛素分子数与观察到的胰岛素分子数与从125i标记的胰岛素结合研究中计算出的受体数一致。在细胞的细胞质中未观察到铁蛋白-胰岛素，但在表面连接的小泡的凹凸侧发现。这些表面相连的小泡是一个肺泡样的质膜内陷系统的一部分，它在细胞质中向各个方向投射，通过薄切片可以表现为嗜饮性微泡。对铁蛋白-胰岛素结合的形态学观察得到了支持，发现125i标记的胰岛素结合几乎完全局限于高纯度的质膜，这些质膜是在125i标记的胰岛素孵育后通过脂肪细胞分离得到的。这些数据支持了胰岛素不需要进入细胞就能引起生物学效应的理论，与胰岛素与细胞受体结合的负协同性概念是一致的。
The method for preparing a stable, biologically active, covalently linked ferritin--insulin complex has been modified to provide a 25-fold increase in yield compared to the original procedure while reducing the molar fatio of ferritin to insulin to 1:1 from 40:1. Ultrastructural studies of isolated adipocytes revealed specific binding of ferritin--insulin to the cell surface in irregular clusters associated with the glycocalyx coating. The number of ferritin--insulin molecules observed was consistent with the number of sulin molecules observed was consistent with the number of receptors calculated from 125I-labeled insulin binding studies. The ferritin--insulin was not observed in the cytoplasm of the cell but was found on the convave side of surface connected vesicles. These surface connected vesicles were part of an alveolar-like system of plasma membrane invaginations which project in various directions in the cytoplasm and by thin sectioning can appear as pinocytotic-like microvesicles. The morphological observations on ferritin--insulin binding were supported by the finding that 125I-labeled insulin binding was almost exclusively localized to highly purified plasma membranes isolated by fractionation of adipocytes after incubation with 125I-labeled insulin. These data supported the theory that insulin did not need to enter a cell to cause biological effects and was consistent with the negative cooperativity concept of insulin binding to cell receptors.