Protein-protein interaction detection: methods and analysis

Protein-protein interactions (PPIs) are ubiquitous to cellular process. Proteins are the workhorses that facilitate most biological processes in a cell, including gene expression, DNA replication, transcription, translation, splicing, secretion, cell cycle control, signal transduction, apoptosis, and intermediary metabolism, where PPI plays a crucial role to facilitate their smooth running. Implications about function of any protein can be made via PPI. These implications are based on the premise that the function of unknown proteins may be discovered if captured through their interaction with a protein target of known function. These interactions are critical for the interactomics system of the living cell (or organisms) and abnormal PPIs are the sole reason for several diseases such as Alzheimer's disease and cancer. Extracellular signal basically regulates the activities of cells. Transduction of signals inside the interior of cells depends critically on PPIs between the various signaling molecules and transmembrane proteins. These signals could be for either normal metabolism or even cell death. Not only this, but also PPIs help in carrying proteins from one place to targets (such as from cytoplasm to nucleus in case of the nuclear importin). In most of the cases, one protein carries another protein for proper functioning of cells. In almost all biosynthetic events in cells, enzymes interact or communicate with each other and generate other macromolecules. Regulation of all metabolic events (e.g., negative feedback) and biology of muscle contraction also involves several interactions.