PCMT1 and neurodegenerative disease: To extend this finding and explore its possible relevance to neurodegenerative diseases, we attempted to determine the stoichiometry of isoaspartate accumulation in synuclein in vivo and in vitro. Brain proteins from PIMT knockout mice were separated by 2D electrophoresis followed by on-blot [3H]-methylation to label isoaspartyl proteins, and by immunoblotting to confirm the coincident presence of synuclein.