Protein-protein interactions constitute a major component of the cellular biochemical response network, and protein-protein interaction networks and transcriptional regulatory networks are important for regulating cells and their signals.

I. Yeast two-hybrid system: Yeast two-hybrid system is an important method widely used in protein interactomics research at present. Its principle is that when the target protein and the bait protein specifically bind, the bait protein binds to the promoter of the reporter gene and initiates the expression of the reporter gene in the yeast cell, and if the expression product of the reporter gene is detected, it indicates that there is an interaction between the two, and vice versa, there is no interaction between the two. This technique can be miniaturized and arrayed for large-scale protein interaction studies. In practice, single-hybridization systems, three-hybridization systems, and reverse hybridization systems have been developed according to needs, etc. Angermayr et al. designed a SOS protein-mediated two-hybridization system. The function of membrane proteins can be studied, enriching the yeast two-hybrid system. In addition, the role of the yeast two-hybrid system has been extended to the identification of proteins.

Two, phage display technology: in the encoding phage shell protein gene connected to a monoclonal antibody DNA sequence, when the phage growth, the surface of the corresponding monoclonal antibody is expressed, and then the phage over the column, the column if containing the target protein, it will be with the corresponding antibody specific binding, which is known as phage display technology. This technique is also mainly used to study the interaction between proteins, which not only has the characteristics of high throughput and simplicity, but also has the advantages of directly obtaining the genes, highly selective screening of complex mixtures, and directly evaluating the specificity of mutual binding by appropriately altering the conditions during the screening process. At present, cdna libraries of two special cell lines, human and murine, have been demonstrated with optimized phage display technology, and signaling molecules in the human epithelial growth factor signaling pathway have been isolated.

Three, plasma **** vibration technology: Surface plasmon **** vibration technology (Surface Plasmon Resonance, SPR) has become a new means in protein interaction research. The principle is to use a nanoscale film adsorbed on the "bait protein", when the protein to be tested and the bait protein binding, the film *** vibration properties will change, through the detection of the two proteins can be known by the combination of the two. SPR technology has the advantage that no markers or dyes are required, the reaction process can be monitored in real time. It is fast and safe, and can also be used to detect interactions between proteins and nucleic acids and other biomolecules.

Four, fluorescence energy transfer technology: fluorescence *** vibration energy transfer (FRET ) is widely used in the study of the distance between molecules and their interactions; and fluorescence microscopy, can be quantitatively obtained about the biological vivo proteins, lipids, DNA and RNA spatial and temporal information. With the development of green fluorescent protein (GFP), FRET fluorescence microscopy has the potential to measure the dynamic nature of molecules in living cells in real time. A simple method for quantitatively measuring FRET efficiency and the distance between donor and acceptor is proposed, which requires only the use of a set of filters and the measurement of a ratio, utilizing the emission spectra of the donor and acceptor to eliminate crosstalk between the spectra. The method is simple, fast, and allows real-time quantitative measurement of FRET efficiency and donor-acceptor distance, and is particularly suitable for GFP-based donor-acceptor pairs.

V. Antibody and protein array technology: The emergence of protein microarray technology has brought new ideas to proteomics research. One of the main contents of proteomics research is to study the quantitative change of protein level in different physiological states, miniaturized, integrated, high-throughput antibody microarrays are a very good research tool, and he is also the fastest developing chip in the chip, and has become increasingly mature in terms of technology. Some of these antibody microarrays have been developed for clinical applications, such as tumor marker antibody microarrays, and many others have been applied in various fields.

Sixth, immune *** precipitation technology: immune *** precipitation is mainly used to study protein-protein interactions of a technology, the basic principle is that, in the cell lysate added to the anti-interest protein antibody, incubation and then add with the antibody specifically bound to the binding of Staphylococcus aureus protein A on the beads of Pansobin (SPA), if the cells have a positive interest in binding the target protein, it can be formed and the interest protein, the target protein can be formed. If there is a target protein in the cell that is binding to the protein of interest, a complex can be formed: "target protein - protein of interest - anti-protein of interest antibody - SPA|Pansobin" because SPA|Pansobin is relatively large. large, so that the complex is separated during centrifugation. The four components of the complex were separated again by denaturing polyacrylamide gel electrophoresis. Then by Western blotting, antibodies were used to detect what the target protein was and whether it was a predicted protein. The target protein obtained by this method is naturally bound to the protein of interest in the cell, which is in line with the actual situation in the body, and the protein obtained is highly credible. However, this method has two defects: one is that the binding of the two proteins may not be a direct binding, but there may be a third party in the middle of the bridge role; the second is that it is necessary to predict what the target protein is before the experiment in order to choose the final detection of the antibody, so if the prediction is incorrect, the experiment does not get the results, and the method itself is adventurous.

Seven, pull-down technology: the types of protein interactions are firm-type interactions and temporary interactions. Firm-type interactions are common with multisubunit protein complexes, and are best studied by immuno***precipitation (Co-IP), Pull-down technique, or Far-western method.Pull-down technique uses solid-phase, labeled bait or tagged proteins (biotin-, PolyHis-, or GST-) to fish out from cell lysates interacting with the with the proteins. The Pull-down technique allows for the determination of known interactions between proteins and fished proteins or purified proteins of interest, and the detection of protein interactions from in vitro circuits or translational systems.