Lipid rafts alter the stability and activity of the cholera toxin A1 subunit.

ABSTRACT: Cholera toxin (CT) travels from the cell surface to the endoplasmic reticulum (ER) as an AB holotoxin. ER-specific conditions then promote the dissociation of the catalytic CTA1 subunit from the rest of the toxin. CTA1 is held in a stable conformation by its assembly in the CT holotoxin, but the dissociated CTA1 subunit is an unstable protein that spontaneously assumes a disordered state at physiological temperature. This unfolding event triggers the ER-to-cytosol translocation of CTA1 through the quality control mechanism of ER-associated degradation. The translocated pool of CTA1 must regain a folded, active structure to modify its G protein target which is located in lipid rafts at the cytoplasmic face of the plasma membrane. Here, we report that lipid rafts place disordered CTA1 in a f

SUBMITTER: Ray S 

PROVIDER: S-EPMC3436369 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature