Tsuzuki J, Wu H C
J Cell Physiol. 1982 Oct;113(1):94-8. doi: 10.1002/jcp.1041130116.
Abrin, a potent cytotoxin, was utilized as a probe to elucidate the mechanism by which external proteins are delivered to the cytoplasm of mammalian cells. Abrin bound rapidly to the surface receptors of the Chinese hamster cells (line CHO) and appeared to be internalized immediately without any significant lag. The maximum level of abrin internalization was achieved within eight minutes, based on both biochemical and electron microscopic autoradiographic studies with [125I]abrin. About 10% of the silver grains of internalized [125I] abrin were associated with vesicular structures, irrespective of the incubation time. Inhibition of protein synthesis began 30 minutes postincubation, and this latent period was not dependent on extracellular toxin concentration. SDS-polyacrylamide gel electrophoresis of the internalized [125I]abrin indicated that internalized abrin molecules remained intact even after two hours of incubation.
相思子毒素是一种强效细胞毒素，被用作探针来阐明外源蛋白质被递送至哺乳动物细胞胞质的机制。相思子毒素迅速结合到中国仓鼠细胞（CHO细胞系）的表面受体上，并且似乎立即被内化，没有明显的延迟。基于对[125I]相思子毒素的生化和电子显微镜放射自显影研究，在八分钟内达到了相思子毒素内化的最大水平。无论孵育时间如何，内化的[125I]相思子毒素约10%的银颗粒与囊泡结构相关。孵育30分钟后开始抑制蛋白质合成，并且这个潜伏期不依赖于细胞外毒素浓度。对内化的[125I]相思子毒素进行的SDS-聚丙烯酰胺凝胶电泳表明，即使孵育两小时后，内化的相思子毒素分子仍保持完整。
