Low Affinity Complementation System

The InteraX application was developed by Applied Biosystems (Bedford, MA) in order to monitor protein-protein interaction [207]. A pair of inactive low affinity fi-galactosidase (P gal) deletion mutants is fused to the protein targets of interest Since the affinity of the fragments is low, the interacting proteins drive the fragment complementation and the P-gal activity reflects the protein-protein interaction. 

In one example, the technology was used to study the dimerization of the epidermal growth factor (EGF) receptor. The p-gal mutants were fused to both the extracellular and the transmembrane domains of EGF, and stably expressed in C2C12 cells. The formation of active p-gal was then dependent on the agonist-stimulated dimerization [208]. 

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