Ribi H O, Ludwig D S, Mercer K L, Schoolnik G K, Kornberg R D
Department of Cell Biology, Howard Hughes Medical Institute, Stanford University School of Medicine, CA 94305.
Science. 1988 Mar 11;239(4845):1272-6. doi: 10.1126/science.3344432.
Two-dimensional crystals of cholera toxin bound to receptors in a lipid membrane give diffraction extending to 15 A resolution. Three-dimensional structure determination reveals a ring of five B subunits on the membrane surface, with one-third of the A subunit occupying the center of the ring. The remaining mass of the A subunit appears to penetrate the hydrophobic interior of the membrane. Cleavage of a disulfide bond in the A subunit, which activates the toxin, causes a major conformational change, with the A subunit mostly exiting from the B ring.
霍乱毒素与脂质膜中受体结合形成的二维晶体产生了分辨率高达15埃的衍射。三维结构测定显示，膜表面有一个由五个B亚基组成的环，A亚基的三分之一占据环的中心。A亚基的其余部分似乎穿透了膜的疏水内部。激活毒素的A亚基中的二硫键断裂会引起主要的构象变化，A亚基大部分从B环中退出。
