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The receptor Msn5 exports the phosphorylated transcription factor Pho4 out of the nucleus

A Kaffman1, N M Rank, E M O'Neill

  • 1Department of Biochemistry and Biophysics, University of California at San Francisco, School of Medicine, 94143-0448, USA.

Nature
|December 16, 1998
PubMed

Insights

Phosphorylation of the yeast transcription factor Pho4 triggers its nuclear export. This process utilizes the Msn5 receptor, revealing a key mechanism for controlling protein localization and activity.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Nuclear-cytoplasmic shuttling of proteins regulates their activity.
  • Phosphorylation is a key post-translational modification controlling protein localization.
  • Mechanisms of phosphorylation-induced nuclear export are not fully understood.

Purpose of the Study:

  • Investigate the regulation of yeast transcription factor Pho4 nuclear export.
  • Elucidate the role of phosphorylation in controlling Pho4 localization.
  • Identify the export receptor involved in Pho4 nuclear export.

Main Methods:

  • In vivo and in vitro biochemical assays.
  • Analysis of protein phosphorylation and localization.
  • Yeast genetics and molecular biology techniques.

Main Results:

  • Pho4 export from the nucleus is triggered by phosphorylation mediated by the Pho80-Pho85 complex.
  • Msn5, an importin-beta-family member, acts as the nuclear export receptor for Pho4.
  • Msn5 binds to phosphorylated Pho4 in a Ran-GTP-dependent manner.

Conclusions:

  • Phosphorylation by Pho80-Pho85 directly regulates Pho4 nuclear export.
  • Msn5 mediates the phosphorylation-dependent export of Pho4.
  • This study reveals a fundamental mechanism for controlling protein nuclear export via phosphorylation.

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