Systematic Analysis of Complex Signal Transduction Pathways Using Protein Fragment Complementation Assays

: The state of a signal transduction pathway can be assessed by monitoring a given point, or a signaling node, of interest within that pathway by high content analysis. The activity at these nodes may be correlated with the general effect on cell number and morphology at the same time. Here we describe a method to analyze protein-protein interactions by protein fragment complementation assays. Complex signal transduction pathways become accessible by looking at them in their native cellular context, with all competitive and feedback mechanisms in place. Analyzing protein-protein interactions directly makes this method widely usable for many protein families and is independent of an intrinsic enzymatic activity.