Subcellular colocalization of the cellular and scrapie prion proteins in caveolae-like membranous domains

  • Martin Vey
    Departments of Neurology, Pathology, and Biochemistry and Biophysics, University of California, San Francisco, CA 94143; Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75235; and The Hebrew University—Hadassah Medical School, 91120 Jerusalem, Israel
  • Susanne Pilkuhn
    Departments of Neurology, Pathology, and Biochemistry and Biophysics, University of California, San Francisco, CA 94143; Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75235; and The Hebrew University—Hadassah Medical School, 91120 Jerusalem, Israel
  • Holger Wille
    Departments of Neurology, Pathology, and Biochemistry and Biophysics, University of California, San Francisco, CA 94143; Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75235; and The Hebrew University—Hadassah Medical School, 91120 Jerusalem, Israel
  • Randal Nixon
    Departments of Neurology, Pathology, and Biochemistry and Biophysics, University of California, San Francisco, CA 94143; Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75235; and The Hebrew University—Hadassah Medical School, 91120 Jerusalem, Israel
  • Stephen J. DeArmond
    Departments of Neurology, Pathology, and Biochemistry and Biophysics, University of California, San Francisco, CA 94143; Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75235; and The Hebrew University—Hadassah Medical School, 91120 Jerusalem, Israel
  • Eric J. Smart
    Departments of Neurology, Pathology, and Biochemistry and Biophysics, University of California, San Francisco, CA 94143; Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75235; and The Hebrew University—Hadassah Medical School, 91120 Jerusalem, Israel
  • Richard G. W. Anderson
    Departments of Neurology, Pathology, and Biochemistry and Biophysics, University of California, San Francisco, CA 94143; Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75235; and The Hebrew University—Hadassah Medical School, 91120 Jerusalem, Israel
  • Albert Taraboulos
    Departments of Neurology, Pathology, and Biochemistry and Biophysics, University of California, San Francisco, CA 94143; Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75235; and The Hebrew University—Hadassah Medical School, 91120 Jerusalem, Israel
  • Stanley B. Prusiner
    Departments of Neurology, Pathology, and Biochemistry and Biophysics, University of California, San Francisco, CA 94143; Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75235; and The Hebrew University—Hadassah Medical School, 91120 Jerusalem, Israel

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<jats:p> Results of transgenetic studies argue that the scrapie isoform of the prion protein (PrP <jats:sup>Sc</jats:sup> ) interacts with the substrate cellular PrP (PrP <jats:sup>C</jats:sup> ) during conversion into nascent PrP <jats:sup>Sc</jats:sup> . While PrP <jats:sup>Sc</jats:sup> appears to accumulate primarily in lysosomes, caveolae-like domains (CLDs) have been suggested to be the site where PrP <jats:sup>C</jats:sup> is converted into PrP <jats:sup>Sc</jats:sup> . We report herein that CLDs isolated from scrapie-infected neuroblastoma (ScN2a) cells contain PrP <jats:sup>C</jats:sup> and PrP <jats:sup>Sc</jats:sup> . After lysis of ScN2a cells in ice-cold Triton X-100, both PrP isoforms and an N-terminally truncated form of PrP <jats:sup>C</jats:sup> (PrP <jats:sup>C</jats:sup> -II) were found concentrated in detergent-insoluble complexes resembling CLDs that were isolated by flotation in sucrose gradients. Similar results were obtained when CLDs were purified from plasma membranes by sonication and gradient centrifugation; with this procedure no detergents are used, which minimizes artifacts that might arise from redistribution of proteins among subcellular fractions. The caveolar markers ganglioside GM1 and H-ras were found concentrated in the CLD fractions. When plasma membrane proteins were labeled with the impermeant reagent sulfo- <jats:italic>N</jats:italic> -hydroxysuccinimide-biotin, both PrP <jats:sup>C</jats:sup> and PrP <jats:sup>Sc</jats:sup> were found biotinylated in CLD fractions. Similar results on the colocalization of PrP <jats:sup>C</jats:sup> and PrP <jats:sup>Sc</jats:sup> were obtained when CLDs were isolated from Syrian hamster brains. Our findings demonstrate that both PrP <jats:sup>C</jats:sup> and PrP <jats:sup>Sc</jats:sup> are present in CLDs and, thus, support the hypothesis that the PrP <jats:sup>Sc</jats:sup> formation occurs within this subcellular compartment. </jats:p>

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