Protein-protein interactions: the yeast two-hybrid system.

Yeast two-hybrid systems are powerful tools to identify novel protein-protein interactions and have been extensively used to study viral protein interactions. The most commonly used systems are GAL4-based and LexA-based systems. Over the last decade, a range of modifications and improvements have been made to the original yeast two-hybrid system to expand the scope of molecular interaction assays and to eliminate false positives. Detailed protocols are provided for yeast strain storage, yeast transformation, yeast mating, preparation of growth and selection medium, quantitative reporter gene assays (alpha- and beta-galactosidase liquid assays) and detection of fusion protein by Western blot.