The Yeast Two-Hybrid System
The yeast two-hybrid system is a powerful technique for identifying multiprotein complexes. Using genetically engineered yeast, scientists can identify complexes when specific pairs of interacting proteins activate expression of a reporter gene. One often-used reporter gene is the lacZ gene. When two proteins interact in the yeast cell they activate expression of this gene, allowing yeast cells to metabolize an indicator that turns these cells a different color. The interacting proteins are then identified from the colonies formed by these colored cells. The two-hybrid system has been expanded to use microarrays of cloned yeast genes (see below). These large-scale yeast two-hybrid assays can provide information on thousands of protein-protein interactions. Using this technology, researchers are identifying all the proteins in yeast that interact, and they will then map the complex network of cellular functions to these interacting proteins.
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