In Vivo Imaging of Protein-Protein Interactions

Protein-protein interaction (PPI) plays a pivotal role in a wide variety of cellular events and physiological functions, such as enzymatic activity, signal transduction, immunological recognition, DNA repair/replication, among others (Valdar and Thornton, 2001). In addition, biological events that regulate proliferation, differentiation, and inflammation are also commonly mediated through PPI (Villalobos et al., 2007). Various techniques in molecular biology have been developed to understand the mechanism of these ubiquitous interactions, including qualitative methods such as yeast-two-hybrid screen (Fields and Song, 1989), immunoprecipitation (Williams, 2000), gel-filtration chromatography (Phizicky and Fields, 1995), etc. Meanwhile, quantitative biophysical methods have also been designed which include analytical ultracentrifugation (Hansen et al., 1994), calorimetry (Doyle, 1997), optical spectroscopy (Lakey and Raggett, 1998), etc. A decade ago, an assay for PPI based on ┚-galactosidase (gal) complementation was designed and successfully applied in cells (Wehrman et al., 2002).