MODULATION OF INSULIN RECEPTOR FUNCTION

胰岛素受体C端结构域在调节血管紧张素转换酶中的作用 用一种合成肽研究胰岛素信号转导 Hc)，其结构对应于胰岛素的残基1293-1307 前受体序列。多肽HC增强胰岛素刺激作用 胰岛素受体在无细胞系统和非细胞系统中的自动磷酸化 洋地黄素通透性细胞对基底细胞无明显影响 自磷酸化水平对受体去磷酸化的影响。多肽 通过在其N-末端添加硬脂基部分来修饰，以及 转基因完整中国仓鼠卵巢(CHO)细胞的研究 一种编码人胰岛素受体的表达载体。我们发现 硬脂肽HC对胰岛素刺激的胰岛素的促进作用 受体自动磷酸化对配体刺激无影响 CHO细胞的受体磷酸化活性过表达 IGF-1受体或EGF受体。探讨硬脂酰多肽的作用 在调节胰岛素信号的过程中，我们评估了 磷脂酰肌醇3‘-激酶(PI e’-K)磷酸化为酪氨酸 胰岛素受体底物-1(IRS-1)和磷酸化水平 过度磷酸化凝胶对丝裂原活化蛋白(MAP)激酶的影响 移位分析。用硬脂酰多肽HC负载细胞后， 胰岛素刺激的PI 3‘-K活性增加1.7倍 在抗IRS-1免疫沉淀物中检测到，MAP增加1.8倍 蛋白激酶过度磷酸化的物种。总而言之，我们的数据提供 序列1293-1307的重要作用的证据 胰岛素受体在生物传递中的C末端 并至少部分地解释了受体的专一性。

The role of the insulin receptor C-terminal domain in the regulation of insulin signal transduction was studied with a synthetic peptide (peptide HC) whose structure corresponds to residues 1293-1307 of the insulin proreceptor sequence. Peptide HC enhanced insulin-stimulated autophosphorylation of the insulin receptor in cell-free systems and in digitonin-permeabilized cells without any detectable effect on basal authophosphorylation levels on receptor dephosphorylation. The peptide was modified by addition of a stearyl moieties at its N-terminus, and introduced in intact Chinese hamster ovary (CHO) cells transfected with an expression plasmid encoding the human insulin receptor. We found that stearyl-peptide HC enhanced several fold insulin-stimulated insulin receptor autophosphorylation while having no effect on ligand-stimulated receptor phosphorylation activity in CHO cells overexpressing either the IGF-1 receptor or EGF receptor. To explore the effect of stearyl-peptide HC in regulating insulin signaling, we evaluated the association of phosphatidylinositol 3'-kinase (PI e'-K) to tyrosine phosphorylated insulin receptor substrate-1 (IRS-1), and the levels of phosphorylation of mitogen-activated protein (MAP) kinase by hyperphosphorylation gel shift assay. Loading of cells with stearyl-peptide HC resulted in a 1.7-fold increase in the amount of insulin-stimulated PI 3'-K activity detected in anti-IRS-1 immunoprecipitates, and a 1.8-fold increase in MAP kinase hyperphosphorylated species. Taken together our data provide evidence for the important role of the sequence 1293-1307 in the C-terminus of the insulin receptor in the transmission of biological effects and could account, as least in part, for receptor specificity.