Protein Interaction Immunoprecipitation (IP)

Immunoprecipitation is a technique in which an antigen is isolated by binding to a specific antibody attached to a sedimentable matrix. It is also used to analyze protein fractions separated by other techniques such as gel filtration or density gradient sedimentation. The source of antigen for immunoprecipitation can be unlabeled cells or tissues, metabolically or intrinsically labeled cells, or in vitro-translated proteins. This unit describes a wide range of immunoprecipitation techniques, using either suspension or adherent cells lysed by various means.Usually, plasmas transfected cells or natural cells are ideal sample for immunoprecipitation.

Protein–protein interactions (PPIs) refer to physical contacts established between two or more proteins as a result of biochemical events and/or electrostatic forces.

In fact, most of proteins don't act alone, they always interact with others. Diverse essential molecular processes within a cell are carried out by molecular machines that are built from a large number of protein components organized by their protein interactions. Indeed, these interactions are at the center of the entire interactomics system of any living cell and so, unsurprisingly, aberrant protein interactions are on the basis of multiple diseases, such as Creutzfeld-Jacob, Alzheimer's disease, and cancer.

Signal transduction

The activity of the cell is regulated by extracellular signals. Signals transduct to inside and/or along the interior of cells depends on protein interactions between the various signaling molecules. This process, called signal transduction, plays a fundamental role in many biological processes and in many diseases (e.g. Parkinson's disease and cancer).

Transport across membranes

A protein may be binding with another protein for go into the cell (for example, from cytoplasm to nucleus or vice versa in the case of the nuclear pore importins).

Cell metabolism

In many biosynthetic processes enzymes interact with each other or other proteins to produce small compounds or other macromolecules.
Muscle contraction
Physiology of muscle contraction involves several interactions. Myosin filaments act as molecular motors and by binding to actin enables filament sliding. Besides, members of the skeletal muscle lipid droplet-associated proteins family associate with other proteins, as activator of adipose triglyceride lipase and its coactivator comparative gene identification-58, to regulate lipolysis in skeletal muscle.