We request a ThermoFisher LTQ XL linear ion trap with an electron transfer dissociation source to be placed in the Oregon Health &Science University's Proteomics Shared Resource (PSR). Due to the high sensitivity and fast scan rates, this instrument will be used to identify proteins in complex mixtures of precipitated proteins in Protein/Protein or Protein/Drug interaction studies, preparations of subcellular fractions, extracts of microdissected tissues, and immuno-depleted serum samples. The electron transfer dissociation source will be used to improve the detection and localization of post-translational modifications, including phosphorylation, glycosylation and isomerization of aspartate. The instrument will play a crucial role in 12 diverse projects studying the causes of human disease including cataracts, hearing loss, neurodegenerative disease in the young and old, cancer, methamphetamine addiction, hemochromatosis, and diabetes. The introduction of this instrument will fulfill the growing needs of the researchers at the Oregon Health &Sciences University to incorporate state-of-the-art tools in proteomics into their research. This will speed their progress of discovery to improve the detection and treatment of human disease. PUBLIC HEALTH RELEVANCE: We request funding for an LTQ XL ion trap mass spectrometer to identify proteins and detect their modifications. This instrument will be placed in a shared core facility and will help investigate the cause and treatment of diseases ranging from cancer to hearing loss at the Oregon Health &Science University.