A comprehensive analysis of protein-protein interactions in Saccharomyces cerevisiae

Two large-scale yeast two-hybrid screens were undertaken to identify protei n-protein interactions between full-length open reading frames predicted fr om the Saccharomyces cerevisiae genome sequence. In one approach, we constr ucted a protein array of about 6,000 yeast transformants, with each transfo rmant expressing one of the open reading frames as a fusion to an activatio n domain. This array was screened by a simple and automated procedure for 1 92 yeast proteins, with positive responses identified by their positions in the array, In a second approach, we pooled cells expressing one of about 6 ,000 activation domain fusions to generate a library. We used a high-throug hput screening procedure to screen nearly all of the 6,000 predicted yeast proteins, expressed as Gal4 DNA-binding domain fusion proteins, against the library, and characterized positives by sequence analysis. These approache s resulted in the detection of 957 putative interactions involving 1,004 S. cerevisiae proteins, These data reveal interactions that place functionall y unclassified proteins in a biological context, interactions between prote ins involved in the same biological function, and interactions that link bi ological functions together into larger cellular processes. The results of these screens are shown here.