Analysis of Covalent Modifications of Amyloidogenic Proteins Using Two-Dimensional Electrophoresis: Prion Protein and Its Sialylation.

A number of proteins associated with neurodegenerative disease undergo several types of posttranslational modifications. They include N-linked glycosylation of the prion protein and amyloid precursor protein, phosphorylation of tau and α-synuclein. Posttranslational modifications alter physical properties of proteins including their net and surface charges, affecting their processing, life-time and propensity to acquire misfolded, disease-associated states. As such, analysis of posttranslational modifications is important for understanding the mechanisms of pathogenesis. Recent studies documented that sialylation of the disease-associated form of the prion protein or PrPSc controls the fate of prions in an organism and outcomes of prion infection. For assessing sialylation status of PrPSc, we developed a reliable protocol that involves two-dimensional electrophoresis followed by Western blot (2D). The current chapter describes the procedure for the analysis of sialylation status of PrPSc from various sources including central nervous system, secondary lymphoid organs, cultured cells, or PrPSc produced in Protein Misfolding Cyclic Amplification.