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Science 12 August 2005:
Vol. 309. no. 5737, p. 985
DOI: 10.1126/science.309.5737.985j
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Figure 1 Cholera toxin catalyzes reactions that lead to the devastating diarrhea characteristic of the disease. The toxin is activated by a family of human G proteins, adenosine diphosphate-ribosylation factors (ARFs), which normally act as molecular switches through binding effector proteins in eukaryotic cells. O'Neal et al. (p. 1093) now report high-resolution structures of the catalytic cholera toxin A1 subunit (CTA1) bound to ARF-guanosine triphosphate (GTP), with and without substrate bound. Although cholera toxin is not structurally similar to human protein partners of ARF, the toxin:ARF-GTP interface mimics ARFGTP recognition of human effector proteins. The binding causes conformational changes that open the CTA1 active site to substrate access.

CREDIT: O'NEAL ET AL.




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