Research Articles

Three-dimensional structure of cholera toxin penetrating a lipid membrane

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Science  11 Mar 1988:
Vol. 239, Issue 4845, pp. 1272-1276
DOI: 10.1126/science.3344432

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.