7.5 Summary of Section 7
Site-directed mutagenesis is an important technique for studying protein function. Using recombinant DNA technology, selected amino acids can be substituted with different residues to alter the structure and function of a protein. One widely used method employs primer extension. SDM studies can help identify residues that are critical for interactions or catalytic activity.
Protein–protein interactions can be studied in a number of different ways – using biochemical or physical methods or using library-based methods.
Physical methods include variations on ‘fishing’ approaches in which a bait protein is used to physically pull interacting proteins out of a mixture of proteins. Such methods include protein affinity chromatography and co-immunoprecipitation.
Chemical cross-linking of proteins can provide information on interacting residues, and surface plasmon resonance can be used to study the kinetics of binding interactions between proteins.
Library-based methods for studying protein–protein interactions rely on recombinant DNA technology and include the two-hybrid system and phage display. An advantage of these techniques is that the gene encoding the interacting protein is immediately available for further studies.
Proteomics is the study of all the proteins expressed in an organism or cell in terms of their function, structure, modifications and interactions, indeed all aspects of their biochemistry.