Knutson V P
Department of Pharmacology, University of Texas Medical School, Houston 77225.
J Biol Chem. 1988 Oct 5;263(28):14146-51.
The design and characterization of a six-amino acid-containing peptide that binds insulin is described. The amino acid sequence of the insulin-binding peptide (IBP) was determined from the strand of DNA complementary to the strand of DNA coding for the insulin molecule in the domain of the insulin monomer believed to interact with the insulin receptor. The IBP (Cys-Val-Glu-Glu-Ala-Ser) binds specifically to insulin in a saturable manner with a Kd of 3 nM. This binding process is time dependent and slightly temperature dependent, and the peptide appears to interact with insulin near the carboxyl terminus of the B-chain of insulin. Incubation of insulin with the peptide decreases insulin binding to the insulin receptor by 50%, with no effect on the affinity of insulin for the receptor and no effect on cellular insulin-stimulated deoxyglucose uptake. A polyclonal antibody produced against the IBP will inhibit specific insulin binding to intact cells by approximately 50%, with no effects on insulin-stimulated glucose uptake. From this data, we suggest that there are at least two domains of the insulin molecule through which it interacts with its receptor, the "binding region" of insulin, which is the domain blocked by the IBP, and the "message region" of insulin, through which insulin not only binds to the receptor, but also generates the cellular signal.
本文描述了一种含六个氨基酸的胰岛素结合肽的设计与特性。胰岛素结合肽（IBP）的氨基酸序列是从与胰岛素单体中被认为与胰岛素受体相互作用的结构域内编码胰岛素分子的DNA链互补的DNA链中确定的。IBP（半胱氨酸-缬氨酸-谷氨酸-谷氨酸-丙氨酸-丝氨酸）以饱和方式特异性结合胰岛素，解离常数（Kd）为3 nM。这种结合过程具有时间依赖性且略微依赖温度，该肽似乎与胰岛素B链羧基末端附近的胰岛素相互作用。胰岛素与该肽一起孵育会使胰岛素与胰岛素受体的结合减少50%，对胰岛素与受体的亲和力以及细胞胰岛素刺激的脱氧葡萄糖摄取没有影响。针对IBP产生的多克隆抗体将抑制胰岛素与完整细胞的特异性结合约50%，对胰岛素刺激的葡萄糖摄取没有影响。根据这些数据，我们认为胰岛素分子至少有两个结构域通过它们与受体相互作用，即胰岛素的“结合区域”，它是被IBP阻断的结构域，以及胰岛素的“信号区域”，胰岛素不仅通过该区域与受体结合，还产生细胞信号。
