PerspectiveMolecular Biology

New Proteases in a Ubiquitin Stew

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Science  18 Oct 2002:
Vol. 298, Issue 5593, pp. 549-552
DOI: 10.1126/science.1078097


  • Metalloproteases in large protein complexes.

    (A) The COP9-signalosome (CSN) catalyzes the removal of the Rub ubiquitin-like protein from the SCF ubiquitin ligase and thereby modulates SCF ligase activity, probably by stimulating dissociation of the ubiquitin-conjugating enzyme (UBC). The yeast Sic1 protein is an example of an SCF substrate. (B) A polyubiquitin tag directs proteins to the proteasome, but it must be removed to allow degradation of the protein substrate. The lid component of the 19S regulatory complex of the proteasome is similar in composition and organization to the CSN.

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