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The RNA export factor Mex67 functions as a mobile nucleoporin

Carina Patrizia Derrer1, Roberta Mancini1, Pascal Vallotton1

  • 1Institute of Biochemistry, ETH Zürich, Zurich, Switzerland.

The Journal of Cell Biology
|November 23, 2019
PubMed

Insights

The RNA export factor Mex67 is crucial for mRNA transport through the nuclear pore complex (NPC). This study reveals Mex67 acts as a mobile NPC component, facilitating mRNA translocation to the cytoplasm.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Messenger RNA (mRNA) export from the nucleus is vital for gene expression.
  • The RNA export factor Mex67 is essential for mRNA transport via the nuclear pore complex (NPC) in yeast.
  • The precise molecular mechanism of Mex67-mediated mRNA export remains unclear.

Purpose of the Study:

  • To investigate the molecular mechanism by which Mex67 facilitates mRNA export.
  • To elucidate the role of Mex67's interaction with mRNA and the NPC.
  • To determine the functional localization of Mex67 during mRNA export.

Main Methods:

  • Quantitative fluorescence microscopy in live budding yeast cells.
  • Analysis of Mex67 localization and interaction with mRNA and NPC components.
  • Functional complementation assays using Mex67-Nup116 fusion protein.

Main Results:

  • Mex67 shows minimal interaction with mRNA in the nucleus and localizes to the NPC independently of mRNA.
  • Mex67 binds to FG repeats within the NPC, and this interaction is unaffected by the ATPase Dbp5.
  • The essential function of Mex67 is localized to the NPC, as demonstrated by rescuing a MEX67 deletion with a Mex67-Nup116 fusion.

Conclusions:

  • Mex67 functions as a mobile component of the NPC.
  • Mex67 receives mRNA export substrates within the NPC's central channel.
  • This mechanism facilitates the translocation of mRNA from the nucleus to the cytoplasm.

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