Donner D B, Corin R E
J Biol Chem. 1980 Oct 10;255(19):9005-8.
125I-insulin dissociated from rat hepatocytes and liver plasma membranes with a time course suggestive of more than a single kinetic process. Dissociation curves were resolved into rapidly and slowly dissociating components. Increasing times of hormone-cell or hormone-membrane incubation prior to the initiation of dissociation increased the proportion of slowly dissociable 125I-insulin and decreased the proportion of rapidly dissociating hormone. The rates of loss of rapidly and slowly dissociating 125I-insulin, 1 to 2 x 10(-3) and 2 to 7 x 10(-5) s-1, respectively, were the same in cell and membrane incubates. The capacity of liver membranes and hepatocytes to bind 125I-insulin in a slowly dissociable state was saturable with respect to insulin concentration (approximately 10(-8) M). The observation of the same physical process in both cells and plasma membranes demonstrates a distinct role for receptors at the exterior surface of target cells in the retention of insulin.
125I标记的胰岛素从大鼠肝细胞和肝细胞膜上解离，其时间进程表明存在不止一个动力学过程。解离曲线被分解为快速解离和缓慢解离的组分。在开始解离之前，增加激素与细胞或激素与膜的孵育时间，会增加缓慢解离的125I标记胰岛素的比例，降低快速解离激素的比例。在细胞和膜孵育物中，快速解离和缓慢解离的125I标记胰岛素的损失速率分别为1至2×10⁻³和2至7×10⁻⁵ s⁻¹，两者相同。肝细胞膜和肝细胞以缓慢解离状态结合125I标记胰岛素的能力相对于胰岛素浓度（约10⁻⁸ M）是可饱和的。在细胞和质膜中观察到相同的物理过程，表明靶细胞外表面的受体在胰岛素滞留中具有独特作用。
