Shimizu N, Shimizu Y, Miskimins W K
Cell Struct Funct. 1984 Sep;9(3):203-12. doi: 10.1247/csf.9.203.
We have conjugated epidermal growth factor (EGF) with the A subunit of ricin (RICa) via a dithiopropionyl linkage. The EGF-RICa conjugate was competitive with [125I]EGF for binding to cell surface EGF receptors. Entry of the conjugate into cells was seen within 10 min at 37 degrees C and inhibition of protein synthesis was seen within 90 min. The blockage of protein synthesis continued for more than 20 h in sensitive cells. Protein synthesis in EGF receptor-deficient cells was not affected. The conjugate killed human epidermoid carcinoma (A431) cells, mouse 3T3 fibroblasts and Chinese hamster lung (CHL) cells with identical efficiencies (ED50 = 2 X 10(-9) M). The EGF-RICa conjugate was used as a selection agent and several resistant variants were isolated from CHL cells. These variants showed various degrees of [125I]EGF binding capacity. Some other characteristics of the variants are also described.
我们已通过二硫代丙酰连接将表皮生长因子（EGF）与蓖麻毒素A亚基（RICa）偶联。EGF-RICa偶联物与[125I]EGF竞争结合细胞表面的EGF受体。在37℃下10分钟内可见偶联物进入细胞，90分钟内可见蛋白质合成受到抑制。在敏感细胞中，蛋白质合成的阻断持续超过20小时。EGF受体缺陷细胞中的蛋白质合成未受影响。该偶联物以相同效率（ED50 = 2×10^(-9) M）杀死人表皮样癌（A431）细胞、小鼠3T3成纤维细胞和中国仓鼠肺（CHL）细胞。EGF-RICa偶联物用作选择剂，从CHL细胞中分离出几种抗性变体。这些变体表现出不同程度的[125I]EGF结合能力。还描述了这些变体的一些其他特征。
