ChIRP-MS: RNA-Directed Proteomic Discovery.

Comprehensive identification of RNA-binding proteins by mass spectrometry (ChIRP-ms) is a novel technique for studying endogenous ribonucleoprotein complexes. ChIRP-ms is robust across a wide range of expression level, from abundant housekeeping RNAs (e.g., spliceosomal U RNAs) to relatively lowly expressed RNAs (e.g., Xist). In vivo RNA-protein interactions are chemically cross-linked, and purified using biotinylated antisense oligonucleotides against RNA of interest. Coprecipitated proteins are gently eluted, and identified by mass-spectrometry (for discovery) or by western blotting (for validation).