Practice question

Tissue-specific protein-protein interactions reflect context-dependent complexes regulating differentiation and signaling. Co-immunoprecipitation preserves native interactions by antibody capture of bait protein and associated partners from lysates, suitable for tissue extracts. RNA immunoprecipitation detects RNA-protein contacts. Western blot alone measures protein abundance but not interaction. Site-directed mutagenesis artificially introduces point mutations to test functional domains in recombinant systems, typically in heterologous cell lines, rather than probing endogenous interaction landscape across tissues. It assesses importance of residues but does not detect complexes directly, making it unsuitable as primary method for analyzing native protein-protein interactions.