Practice question

Co-immunoprecipitation is standard biochemical technique to detect protein-protein interactions under native conditions. Cellular lysates prepared in non-denaturing buffer are incubated with antibody specific to bait protein immobilized on Protein A or G agarose beads. Interacting prey proteins co-precipitate with bait, are eluted and detected by Western blotting. Successful co-precipitation indicates physiological association within complex, signalosome or regulatory scaffold. It does not detect direct DNA binding or amplify RNA. Therefore it specifically precipitates interacting proteins, distinguishing it from ChIP or nucleic acid amplification methods.