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alpha4 phosphoprotein interacts with EDD E3 ubiquitin ligase and poly(A)-binding protein

William J McDonald1, Shirley M Sangster, Lori D Moffat

  • 1Faculty of Medicine, Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.

Journal of Cellular Biochemistry
|June 15, 2010
PubMed

Insights

Mammalian alpha4 phosphoprotein interacts with EDD E3 ubiquitin ligase and poly(A)-binding protein (PABP). This expands alpha4

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Mammalian alpha4 phosphoprotein is a key regulator in the mTOR pathway, influencing ribogenesis, translation initiation, and cell-cycle progression.
  • alpha4 is known to interact with protein phosphatase 2A catalytic subunit (PP2Ac), modulating its activity.

Purpose of the Study:

  • To identify novel protein partners of alpha4.
  • To investigate the interaction between alpha4, EDD E3 ubiquitin ligase, and poly(A)-binding protein (PABP).
  • To elucidate the functional implications of these interactions within the mTOR pathway.

Main Methods:

  • Yeast two-hybrid screening using alpha4 as bait.
  • Immunoprecipitation/immunoblotting (IP/IB) analyses to confirm protein-protein interactions.
  • Deletion mutant analysis to map binding sites.

Main Results:

  • EDD E3 ubiquitin ligase was identified as a novel binding partner of alpha4.
  • alpha4 physically interacts with both EDD and PABP in various mammalian cell lines.
  • EDD binds to the C-terminal region of alpha4, distinct from the PP2Ac binding site.

Conclusions:

  • alpha4 interacts with multiple proteins, including PP2Ac, EDD, and PABP.
  • These interactions suggest alpha4's involvement in diverse steps of the mTOR pathway, from translation initiation to cell-cycle progression.
  • The discovery of EDD and PABP as alpha4 interactors expands our understanding of mTOR pathway regulation.

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