Division of Medical Genetics and Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Dev Biol. 1981 Jun;84(2):417-24. doi: 10.1016/0012-1606(81)90410-3.
We have compared insulin binding by heart cells at 7 and 14 days of development. Species specificity, optimum pH, temperature relationships, and time to equilibrium for binding of insulin were the same in both 7 and 14-day systems. Curvilinear Scatchard plots for chicken insulin binding were demonstrated. Binding affinities and capacities were calculated based on a two-receptor model including a specific high-affinity receptor and a less specific low-affinity receptor that bound insulin and other growth peptides. Apparent association constants (K(A)) were 4.0 and 0.05 nM(-1) and binding capacities were 600 and 9000 sites per cell for high- and low affinity receptors, respectively. We have also investigated the ability of insulin to regulate binding to its own receptors. Chick heart cells from 7- and 14-day embryos, cultured for 44 hr in insulin-enriched medium (3.4 microM), bound 50% less insulin (down-regulated) than control cells. At both developmental stages, down regulation was primarily a reduction in binding to the high-affinity receptor. The low-affinity receptor was less susceptible to down regulation and retained its ability to mediate maximal insulin stimulation of amino acid transport.
我们比较了第 7 天和第 14 天发育的心脏细胞中的胰岛素结合情况。在这两种 7 天和 14 天的系统中，胰岛素结合的物种特异性、最佳 pH 值、温度关系和达到平衡的时间都是相同的。鸡胰岛素结合的曲线 Scatchard 图得到了证明。根据包括特异性高亲和力受体和结合胰岛素和其他生长肽的非特异性低亲和力受体的双受体模型，计算了结合亲和力和容量。高亲和力受体的表观缔合常数（K(A)）为 4.0 和 0.05 nM(-1)，结合容量分别为 600 和 9000 个/细胞。我们还研究了胰岛素调节其自身受体结合的能力。在富含胰岛素的培养基（3.4 microM）中培养 44 小时的 7 天和 14 天胚胎的鸡心脏细胞，与对照细胞相比，胰岛素结合减少了 50%（下调）。在这两个发育阶段，下调主要是高亲和力受体结合的减少。低亲和力受体对下调的敏感性较低，并保留了其介导胰岛素对氨基酸转运的最大刺激的能力。
