Accession Number:

ADA443105

Title:

Identification of Genes Regulated by Proteolysis

Descriptive Note:

Final rept. 1 Jul 2001-30 Jun 2005

Corporate Author:

HARVARD MEDICAL SCHOOL BOSTON MA

Personal Author(s):

Report Date:

2005-07-01

Pagination or Media Count:

54.0

Abstract:

Substrate selection in ubiquitination reactions is achieved by ubiquitin ligases, which simultaneously bind both the target protein and a ubiquitin conjugating enzyme. We have developed a phosphopeptide based approach to facilitate the identification of ubiquitin ligases e.g. F-box proteins that recognize regulatory proteins in a phosphorylation-dependent manner. Thus far, we have used this approach to identify substrates of two F-box proteins, Fbw7 and beta-TRCP. Cyclin E associates with Fbw7 through a phosphodegron near its C-terminus. Experiments in vitro and in vivo have identified critical phosphorylation sites in this degron that are required for interaction with Fbw7. Interestingly, this motif is found in a number of other unstable oncogenic proteins, including c-myc, c-jun, and SREBP. In a second series of studies, we have identified the cell cycle regulatory protein Cdc25A as a target of the beta-TRCP protein. We have found that Chk1 phosphorylates Cdc25A in response to DNA damage to generate a priming event that facilitates phosphorylation of Cdc25A on a motif that then binds to beta-TRCP. Using biochemical and genetic techniques, we demonstrate that this interaction is required for regulated proteolysis of Cdc25A.

Subject Categories:

  • Biochemistry
  • Genetic Engineering and Molecular Biology
  • Medicine and Medical Research

Distribution Statement:

APPROVED FOR PUBLIC RELEASE