Proteomic analysis of [PSI+] yeast strain

The yeast Sup35 protein is a subunit of the translation termination factor, and its conversion to the [PSI+] prion state leads to more translational read-through. Although extensive studies have been done on [PSI+], changes at the proteomic level have not been performed exhaustively. We therefore used a SILAC-based quantitative mass spectrometry approach and identified 4187 proteins from both [psi-] and [PSI+] strains. Surprisingly, there was very little difference between the two proteomes under standard growth conditions.