This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The accumulation of protein aggregates is associated with many neurodegenerative diseases. The presence of these protein aggregates is direct evidence that normal protein metabolism is disrupted. Prions are a primary example of this effect, as they are infectious proteinaceous particles. Although strains of prions have been isolated which differ in incubation time and pathology, there is no nucleic acid component of the prion particles. Infection requires only that normal protein turnover is diverted to the formation of new aggregates. Understanding the propagation of prion disease and how these aggregates cause neurodegeneration requires that we investigate changes in protein turnover due to prion infection. Using nitrogen isotope labeling we will measure protein turnover on a proteome-wide scale to assess perturbations in global protein turnover during prion disease.