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The Doc1 subunit is a processivity factor for the anaphase-promoting complex.

Nature cell biology | Nov 4, 2002

http://www.ncbi.nlm.nih.gov/pubmed/12402045

Ubiquitin-mediated proteolysis of securin and mitotic cyclins is essential for exit from mitosis. The final step in ubiquitination of these and other proteins is catalysed by the anaphase-promoting complex (APC), a multi-subunit ubiquitin-protein ligase (E3). Little is known about the molecular reaction resulting in APC-dependent substrate ubiquitination or the role of individual APC subunits in the reaction. Using a well-defined in vitro system, we show that highly purified APC from Saccharomyces cerevisiae ubiquitinates a model cyclin substrate in a processive manner. Analysis of mutant APC lacking the Doc1/Apc10 subunit (APC(doc1 Delta)) indicates that Doc1 is required for processivity. The specific molecular defect in APC(doc1 Delta) is identified by a large increase in apparent K(M) for the cyclin substrate relative to the wild-type enzyme. This suggests that Doc1 stimulates processivity by limiting substrate dissociation. Addition of recombinant Doc1 to APC(doc1 Delta) fully restores enzyme function. Doc1-related domains are found in mechanistically distinct ubiquitin-ligase enzymes and may generally stimulate ubiquitination by contributing to substrate-enzyme affinity.

Pubmed ID: 12402045 RIS Download

Mesh terms: Anaphase | Anaphase-Promoting Complex-Cyclosome | Apc10 Subunit, Anaphase-Promoting Complex-Cyclosome | Cell Cycle | Cell Cycle Proteins | Dose-Response Relationship, Drug | Kinetics | Models, Biological | Mutation | Protein Binding | Protein Structure, Tertiary | Recombinant Proteins | Saccharomyces cerevisiae | Saccharomyces cerevisiae Proteins | Substrate Specificity | Time Factors | Ubiquitin | Ubiquitin-Protein Ligase Complexes | Ubiquitin-Protein Ligases

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Associated grants

  • Agency: NIGMS NIH HHS, Id: GM53270
  • Agency: NIGMS NIH HHS, Id: R01 GM053270

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