The C-terminal globular domain of the prion protein is necessary and sufficient for import into the endoplasmic reticulum

J Biol Chem. 2004 Feb 13;279(7):5435-43. doi: 10.1074/jbc.M309570200. Epub 2003 Nov 26.

Abstract

The mammalian prion protein (PrP) is composed of an unstructured flexible N-terminal region and a C-terminal globular domain. We examined the import of PrP into the endoplasmic reticulum (ER) of neuronal cells and show that information present in the C-terminal globular domain is required for ER import of the N terminus. N-terminal fragments of PrP, devoid of structural domains located in the C terminus, remained in the cytosol with an uncleaved signal peptide and were rapidly degraded by the proteasome. Conversely, the separate C-terminal domain of PrP, comprising the highly ordered helix 2-loop-helix 3 motif, was entirely imported into the ER. As a consequence, two PrP mutants linked to inherited prion disease in humans, PrP-W145Stop and PrP-Q160Stop, were partially retained in the cytosol. The cytosolic fraction was characterized by an uncleaved N-terminal signal peptide and was degraded by the proteasome. Our study identified a new regulatory element in the C-terminal globular domain of PrP necessary and sufficient to promote import of PrP into the ER.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Blotting, Western
  • Cell Membrane / metabolism
  • Cell Survival
  • Cells, Cultured
  • Codon, Terminator
  • Cytosol / metabolism
  • Endopeptidase K / chemistry
  • Endopeptidase K / pharmacology
  • Endoplasmic Reticulum / metabolism*
  • Mice
  • Microsomes / metabolism
  • Mutation
  • Precipitin Tests
  • Prions / chemistry*
  • Prions / metabolism
  • Protein Biosynthesis
  • Protein Sorting Signals
  • Protein Structure, Tertiary
  • Protein Transport
  • Subcellular Fractions
  • Time Factors
  • Transfection

Substances

  • Codon, Terminator
  • Prions
  • Protein Sorting Signals
  • Endopeptidase K