Wild-type Shadoo proteins convert to amyloid-like forms under native conditions

J Neurochem. 2010 Apr;113(1):92-104. doi: 10.1111/j.1471-4159.2010.06575.x. Epub 2010 Jan 8.


The cellular prion protein PrP(C) refolds into a beta-sheet enriched, infectivity-associated form called PrP(Sc). Shadoo (Sho) is a newly discovered glycoprotein that is also expressed in the adult brain. Wild type (wt) mouse Sho consists of an arginine-rich region, a hydrophobic central domain of five tandem A/LAAG amino acid repeats R1-R5 with similarity to the hydrophobic domain of PrP(C), and a C-terminal domain with one N-linked carbohydrate. As some alanine-rich proteins and PrP with a shortened C-terminal domain form amyloid we investigated conformational properties of wt Sho and polymorphic variants with insertion/deletions centered on R3. Recombinant mouse and sheep Sho converted to an amyloid-like form without recourse to chemical denaturation or acidification. For wt proteins this transition was marked by increased thioflavin T binding, Congo red staining, presence of fibrillar structures by electron microscopy, formation of sodium dodecyl sulfate-resistant complexes and the generation of a C-terminal proteinase K resistant core of 5-8 kDa. Variant Sho proteins differing within the R1-R5 region exhibited most but not all of these properties. Our studies define a proteinase K -resistant signature fragment for the amyloid fold of Sho and raise the question of a physiological role for this form of the wt protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Amyloid / immunology
  • Amyloid / metabolism*
  • Amyloid / ultrastructure
  • Animals
  • Congo Red
  • Culture Media, Conditioned / pharmacology
  • Endopeptidase K / pharmacology
  • GPI-Linked Proteins
  • Mice
  • Microscopy, Electron, Transmission / methods
  • Nerve Tissue Proteins / drug effects
  • Nerve Tissue Proteins / immunology
  • Nerve Tissue Proteins / metabolism*
  • Nerve Tissue Proteins / ultrastructure
  • Neuroblastoma / chemistry
  • Peptide Fragments / chemistry
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • PrPC Proteins / chemistry
  • PrPC Proteins / genetics
  • PrPC Proteins / metabolism
  • Prions / chemistry
  • Prions / genetics
  • Prions / metabolism
  • Protein Binding / drug effects
  • Protein Binding / physiology
  • Protein Conformation / drug effects
  • Protein Folding / drug effects
  • Protein Structure, Tertiary / drug effects
  • Sheep
  • Transfection / methods


  • Amyloid
  • Culture Media, Conditioned
  • GPI-Linked Proteins
  • Nerve Tissue Proteins
  • Peptide Fragments
  • PrPC Proteins
  • Prions
  • Sprn protein, mouse
  • Congo Red
  • Endopeptidase K