Viral proteomics: The emerging cutting-edge of virus research

Zhou, ShengTao; Liu, Rui; Zhao, Xia; Huang, CanHua; Wei, YuQuan

The Y2H system was first introduced by Fields and Song [35] in 1989, and delineates binary physical interactions between proteins. The major advantages of the Y2H system are the facts that it allows one bait to be matched against multiple preys, and that both homo-and heterodimeric interactions can be detected. Moreover, the screens are largely independent of the optimal experimental conditions compared with affinity purification research, because both bait and prey libraries are expressed at comparable levels. Although this may generate nonphysiological protein levels, the increased expression levels might also enhance the sensitivity of the system [36] . Despite its strengths, the Y2H system is defective in its capacity for detecting interactions. On the one hand, it cannot detect cooperative interactions between more than two proteins because of the binary nature of the technique. On the other hand, the interaction occurs in the nucleus, which poses problems for the expression of integral membrane proteins. In addition, certain proteins and transcription factors might independently enable the transcription of the reporter. In addition, ectopically expressed proteins sometimes evade post-translational modification (PTM), thereby ruling out dynamic, PTM-dependent, binary interactions [37] .