C3 and Alzheimer disease: Consideration of both the SNO proteins exclusively found in AD brains (and not in non-AD brains) and those that were found to be statistically increased in AD brains over non-AD brains yielded an integrative protein ranking (table S8) that showed phospholipase D3 (PLD3), p62 sequestosome 1(SQSTM1), and complement component 3 (C3) were among the top S-nitrosylated proteins on the list (Fig. 1H), potentially suggesting previously unknown avenues of pathogenesis for AD.