In vivo quantification of protein–protein interactions in Saccharomyces cerevisiae using bimolecular fluorescence complementation assay

Most of the biological processes are carried out and regulated by dynamic networks of protein–protein interactions. In this study, we demonstrate the feasibility of the bimolecular fluorescence complementation (BiFC) assay for in vivo quantitative analysis of protein–protein interactions in Saccharomyces cerevisiae. We show that the BiFC assay can be used to quantify not only the amount but also the cell-to-cell variation of protein–protein interactions in S. cerevisiae. In addition, we show that protein sumoylation and condition-specific protein–protein interactions can be quantitatively analyzed by using the BiFC assay. Taken together, our results validate that the BiFC assay is a very effective method for quantitative analysis of protein–protein interactions in living yeast cells and has a great potential as a versatile tool for the study of protein function.