NR ACKA
AU Caughey,B.W.; Raymond,G.J.
TI The scrapie-associated form of PrP is made from a cell surface precursor that is both protease- and phospholipase-sensitive
QU The Journal of Biological Chemistry 1991 Sep 25; 266(27): 18217-23
PT journal article
AB A common feature of scrapie and related transmissible spongiform encephalopathies is the accumulation of an abnormal protease-resistant form of PrP which may be the major component of the infectious agent. While it is known that both the normal (protease-sensitive) PrP and protease-resistant PrP are encoded by the same endogenous gene, the nature of the disease-associated modification of PrP is not understood. To study the cellular events leading to the formation of protease-resistant PrP, we have compared its biosynthesis to that of its normal isoform in scrapie-infected mouse neuroblastoma cells. In pulse-chase labeling experiments, the protease-resistant PrP was synthesized and degraded much more slowly than the normal PrP, suggesting that protease-resistant PrP is made from a protease-sensitive precursor. More significantly, we found that the precursor of protease-resistant PrP was eliminated from intact cells by treatments with phosphatidylinositol-specific phospholipase C and trypsin. This demonstrated that, unlike the protease-resistant PrP itself, the precursor is phospholipase- and protease-sensitive and at least transiently found on the cell surface. By these criteria, the precursor of protease-resistant PrP is indistinguishable from the normal PrP isoform. These results indicate that the conversion of PrP to the protease- and phospholipase-resistant state is a post-translational event that occurs after the precursor reaches the cell surface.
IN Das bei scrapieartigen infektiösen spongiformen Encephalopathien akkumulierende proteaseresistente PrP wird wesentlich langsamer als das normale PrP synthetisiert und abgebaut. Es entsteht offenbar aus einem möglicherweise normalen, proteasesensitiven PrP, das durch phosphatidylinositolspezifische Phospholipase C und Trypsin abgebaut werden kann. Die Umwandlung in die proteaseresistente Form scheint an der Zelloberfläche zu erfolgen.
MH Animal; Electrophoresis, Polyacrylamide Gel; Kinetics; Membrane Proteins/metabolism; Mice; Neuroblastoma/microbiology/pathology; Phospholipases/*metabolism; Phosphoric Diester Hydrolases/*metabolism; PrPsc Proteins; Prions/biosynthesis/*metabolism; Protein Precursors/metabolism; Protein Processing, Post-Translational; Trypsin; Tumor Cells, Cultured
AD National Institutes of Health, National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratories, Hamilton, Montana 59840.
SP englisch
PO USA