Identifying protein complexes by affinity purification and mass spectrometry analysis in the rice blast fungus.

Affinity purification and mass spectrometry analyses have been used in various organisms to identify -protein complexes and determine protein-protein interactions in vivo. In comparison with the TAP (tandem affinity purification) tag, the 3× FLAG is a relatively small epitope tag. It has been used to systematically identify protein-protein interactions in the budding yeast. We have used the 3× FLAG tag to isolate proteins co-purified with a number of genes in the rice blast fungus, including TIG1, MST50, PMK1, and MST12. For the example given in the text, five genes homologous to components of the yeast Set3C complex were identified by mass spectrometry analysis.