Analysis of protein-protein interactions in mitochondria by coimmunoprecipitation and chemical cross-linking.

Many different techniques have been employed to analyze protein-protein interactions. Coimmunoprecipitation and chemical cross-linking have been used extensively to study mitochondrial biogenesis. Both techniques have proven to be powerful methods to investigate the sequential interactions of precursor proteins with the various components of the translocation machineries in the mitochondrial membranes. Similarly, protein-protein interactions during processes such as protein synthesis, folding, and degradation can be studied. Moreover, the composition of the oligomeric protein complexes of mitochondria, such as respiratory chain complexes or protein translocation machineries, can be determined. The general principles and protocols of these methods are described and illustrated with typical examples.