Efficient extraction of nucleolar proteins for interactome analyses.

The efficient extraction of proteins from purified cellular organelles is critical for in vitro analyses, including identification of protein complex members by affinity purification-based quantitative proteomic approaches. When applied to purified nucleoli, classic nuclear protein extraction methods inefficiently and selectively release only approximately 50% of proteins. Here, we present a method that can extract up to 90% of nucleolar proteins, and apply it in a quantitative interactomic approach to identify nucleolar interaction partners for a mammalian protein phosphatase.