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Three-dimensional structure of cholera toxin penetrating a lipid membrane
H O Ribi1, D S Ludwig, K L Mercer
1Department of Cell Biology, Howard Hughes Medical Institute, Stanford University School of Medicine, CA 94305.
Science (New York, N.Y.)
|March 11, 1988
Abstract:
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.