Immunoprecipitation (IP) is a method of studying the physical and chemical properties of the protein using the specific binding of antibodies and antigens. This method is often used for protein purification, removal of the target protein, optimization of immunoblotting (WB) effect, determination of protein modification site information, determination of protein degradation rate, determination of enzyme activity.
Co-Immunoprecipitation is a classical method for studying the specific interaction of proteins based on the specificity of antibodies and antigens. It is a important method to determine whether the two proteins are interacting under physiological conditions. The principle is that many protein-protein interactions exist in intact cells are preserved when the cells are cleaved under non-denaturing conditions. If protein A is Co-immunoprecipitated with protein A, then protein Y bound to A in vivo can also be precipitated. This method is often used to determine whether two target proteins are bound in vivo. It also can be used to identify a specific protein Action protein.
Chromatin immunoprecipitation (ChIP) is an important tool for studying the interaction between DNA and protein in vivo. Its basic principle is making the protein and DNA cross-linked together in the physiological state, then breaking it into a certain length chromatin small fragments by ultrasonic waves, Then we use specific antibody of the target protein to precipitate the complex, the specific enrichment of the target protein binding DNA fragments, finally, you can know those genes working with the target protein by the PCR detection.
RNA immunoprecipitation (RIP) is an important means of studying the interaction between RNA and protein in vivo, and its basic principle is to immunoprecipitate the protein that binds RNA in physiological state. The RNA component is then obtained by isolating the antibody-Protein A/G beads complex and finally the target RNA is detected by gene chip or other means.
It can be seen from the above content: CO-IP, CHIP and RIP could achieve different research purposes based on the basic principles. CO-IP is mainly to study the relationship between the target protein X and the protein Y interacting with it. And CHIP is mainly to study the target protein X and the relationship between X and the DNA fragment Y interacting with it. RIP mainly deals with the binding of RNA-binding proteins and RNA. This difference also determines that the operating procedures and the buffer formulations involved are different when performing IP, CO-IP and CHIP, and RIP experiments.