Pappenheimer A M, Brown R
J Exp Med. 1968 Jun 1;127(6):1073-86. doi: 10.1084/jem.127.6.1073.
Using the technique of radioautography, it has been shown that a probable maximum of only 25-50 molecules iodine-125-labeled toxin per cell is bound by human HeLa cells treated with approximately 10(7) molecules of toxin per cell, or just under one saturating dose. Radioautographs of sections from labeled cells locate most if not all of the toxin molecules fixed to the outer cell membrane. Under identical conditions far less label is taken up by mouse L cells. It is probable that the resistance of this species to diphtheria toxin can be accounted for in terms of the failure of mouse cells to bind the toxin protein. The irreversible inhibition of protein synthesis in a living cell culture by a few molecules of toxin located at the cell surface is discussed in relation to the known interaction between toxin, NAD, and transferase II in mammalian cell extracts.
运用放射自显影技术已表明，在用每细胞约10⁷个毒素分子（即略低于一个饱和剂量）处理的人HeLa细胞中，每细胞可能最多仅结合25 - 50个碘 - 125标记的毒素分子。标记细胞切片的放射自显影片显示，固定于细胞膜外的毒素分子即便不是全部，也大部分都能定位。在相同条件下，小鼠L细胞摄取的标记物要少得多。很可能该物种对白喉毒素的抗性可归因于小鼠细胞不能结合毒素蛋白。结合哺乳动物细胞提取物中已知的毒素、NAD和转移酶II之间的相互作用，讨论了位于细胞表面的少数毒素分子对活细胞培养物中蛋白质合成的不可逆抑制作用。
