A transmembrane form of the prion protein contains an uncleaved signal peptide and is retained in the endoplasmic Reticulum.
Although there is considerable evidence that PrP(Sc) is the infectious form of the prion protein, it has recently been proposed that a transmembrane variant called (Ctm)PrP is the direct cause of prion-associated neurodegeneration. We report here, using a mutant form of PrP that is synthesized exclusively with the (Ctm)PrP topology, that (Ctm)PrP is retained in the endoplasmic reticulum and is degraded by the proteasome. We also demonstrate that (Ctm)PrP contains an uncleaved, N-terminal signal peptide as well as a C-terminal glycolipid anchor. These results provide insight into general mechanisms that control the topology of membrane proteins during their synthesis in the endoplasmic reticulum, and they also suggest possible cellular pathways by which (Ctm)PrP may cause disease.
Stewart
R S
RS
Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110.
Drisaldi
B
B
Harris
D A
DA
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D006224:Cricetinae; D003546:Cysteine Endopeptidases / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009097:Multienzyme Complexes / Q000378:metabolism; D016296:Mutagenesis; D011328:Prions / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D021382:Protein Sorting Signals; D014407:Tumor Cells, Cultured
C110396:(ctm)PrP; D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D011328:Prions; D021382:Protein Sorting Signals; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex