The present invention provides AMPAR excitotoxicity mediating polypeptides comprising the GluR2 NT1-3-2 (Y142-K172) amino acid sequence (SEQ ID NO:1) or the GAPDH(2-2-1-1) (I221-E250)amino acid sequence (SEQ ID NO:2). Also disclosed are nucleotide sequences encoding the polypeptides, methods of inhibiting GAPDH association with the GluR2 subunit or p53. Methods of inhibiting AMPA receptor mediated excitotoxicity using the polypeptides and nucleic acids are also disclosed.