Cex1p is a novel cytoplasmic component of the Saccharomyces cerevisiae nuclear tRNA export machinery

EMBO J. 2007 Jan 24;26(2):288-300. doi: 10.1038/sj.emboj.7601493. Epub 2007 Jan 4.

Abstract

The Saccharomyces cerevisiae Yor112wp, which we named Cex1p, was identified using a yeast tRNA three-hybrid interaction approach and an in vivo nuclear tRNA export assay as a cytoplasmic component of the nuclear tRNA export machinery. Cex1p binds tRNA saturably, and associates with the nuclear pore complex by interacting directly with Nup116p. Cex1p co-purifies with the nuclear tRNA export receptors Los1p and Msn5p, the eukaryotic elongation factor eEF-1A, which delivers aminoacylated tRNAs to the ribosome, and the RanGTPase Gsp1p, but not with Cca1p, a tRNA maturation enzyme that facilitates translocation of non-aminoacylated tRNAs across the nuclear pore complex. Depletion of Cex1p and eEF-1A or Los1p significantly reduced the efficiency of nuclear tRNA export. Cex1p interacts with Los1p but not with eEF-1A in vitro. These findings suggest that Cex1p is a component of the nuclear aminoacylation-dependent tRNA export pathway in S. cerevisiae. They also suggest that Cex1p collects aminoacyl-tRNAs from the nuclear export receptors at the cytoplasmic side of the nuclear pore complex, and transfers them to eEF-1A using a channelling mechanism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus / genetics
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Carrier Proteins / physiology*
  • Cell Nucleus / metabolism*
  • Cytoplasm / chemistry
  • Nuclear Pore / metabolism
  • Nuclear Pore Complex Proteins / genetics
  • Nuclear Pore Complex Proteins / metabolism
  • Nucleocytoplasmic Transport Proteins
  • Organisms, Genetically Modified
  • Protein Biosynthesis
  • RNA, Transfer / metabolism*
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / isolation & purification
  • Saccharomyces cerevisiae Proteins / metabolism
  • Saccharomyces cerevisiae Proteins / physiology*
  • Transfer RNA Aminoacylation

Substances

  • ARC1 protein, S cerevisiae
  • Carrier Proteins
  • Cex1 protein, S cerevisiae
  • Los1 protein, S cerevisiae
  • NUP116 protein, S cerevisiae
  • Nuclear Pore Complex Proteins
  • Nucleocytoplasmic Transport Proteins
  • RNA-Binding Proteins
  • Saccharomyces cerevisiae Proteins
  • RNA, Transfer