Analysis of physiological interactions by immunoprecipitation

Immunoprecipitation is performed under non-disruptive conditions to maintain physiological interactions. Protocol 14B can be used to recover and examine the subunit composition of intact oligomeric complexes containing the antigen and other associated macromolecules. The antigen protein is identified in the complex by subsequent immunoblotting or by performing immunoprecipitation imder disruptive conditions (Protocol 14C). 

In Protocol 14C, immunoprecipitation is performed under disruptive conditions in a mixed micelle detergent buffer (RIPA). Most physiological interactions are dissociated imder these stringent conditions, and usually only the antigen protein and veiy tightly-associated proteins are recovered by immunoprecipitation. This method is useful to quantitate levels of pS]methionine labelled protein antigen, and to study synthesis and degradation rates by pulse chase analysis. 

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