Two-hybrid screening (also known as yeast two-hybrid system or Y2H) is a molecular biology technique used to discover protein–protein interactions and protein–DNA interactions by testing for physical interactions (such as binding) between two proteins or a single protein and a DNA molecule, respectively.
The premise behind the test is the activation of downstream reporter gene(s) by the binding of a transcription factor onto an upstream activating sequence (UAS). For two-hybrid screening, the transcription factor is split into two separate fragments, called the binding domain (BD) and activating domain (AD). The BD is the domain responsible for binding to the UAS and the AD is the domain responsible for the activation of transcription. The Y2H is thus a protein-fragment complementation assay.
Read more about Y2H: History, Basic Premise, Fixed Domains, Construction of Expression Plasmids, Recovery of Protein Information, Controlling Sensitivity, Non-fusion Proteins, Split-ubiquitin Yeast Two-hybrid, Host Organism, Strengths, Weaknesses