Scacchi G E, Wald M R, Turyn D, Dellacha J M
Instituto de Química y Fisicoquímica Biológicas (UBA-CONICET), Facultad de Farmacia y Bioquímica, Argentina.
Horm Metab Res. 1988 Jan;20(1):15-9. doi: 10.1055/s-2007-1010738.
Trypsin and alpha-chymotrypsin effects on masked insulin receptors were studied. Phospholipase C treatment, incubation in a high ionic strength buffer or solubilization were used as alternative procedures for the unmasking of insulin receptors. These three methods expose receptor structures which are inaccessible to insulin in the current experimental conditions of binding assays without any significant change in binding affinity. Both exposed and masked receptors proved to be equally sensitive to trypsin and alpha-chymotrypsin degradation. At 25 degrees C, about 5 micrograms trypsin/ml for 50 min or 80 micrograms alpha-chymotrypsin/ml for 200 min were necessary in each case to cause a 50% inhibition of the binding of 125I-iodo insulin to microsomes. The results suggest that masked receptors are only nonfunctional to bind insulin but they are not located in compartments inaccessible to molecules present in the medium.
研究了胰蛋白酶和α-糜蛋白酶对隐蔽型胰岛素受体的作用。使用磷脂酶C处理、在高离子强度缓冲液中孵育或增溶作为使胰岛素受体去隐蔽的替代方法。这三种方法暴露了在当前结合测定实验条件下胰岛素无法接近的受体结构，而结合亲和力没有任何显著变化。已证明暴露型和隐蔽型受体对胰蛋白酶和α-糜蛋白酶降解同样敏感。在25℃下，每种情况下分别需要约5μg胰蛋白酶/ml作用50分钟或80μgα-糜蛋白酶/ml作用200分钟，才能使125I-碘胰岛素与微粒体的结合受到50%的抑制。结果表明，隐蔽型受体仅在结合胰岛素方面无功能，但它们并不位于介质中存在的分子无法接近的区室。
