A protein-protein interaction is an association between proteins through physical contact. Copurification or proximity labeling can suggest an association without establishing that the measured pair contacts directly.
Association between molecules of the same protein. Such contacts can create cooperative assemblies or bridges; visible clustering alone does not establish phase separation.
An assembly containing two protein subunits. A binding unit in an assay need not be a single polypeptide chain.
The possession of several interaction sites in one molecule or assembly. Multiple contacts can give avidity, crosslinking or collective assembly, depending on geometry and partner concentrations.
Reversible biomolecular association with a relatively high dissociation constant under specified conditions. The same equilibrium constant can result from different association and dissociation rates, so weak binding does not alone establish a short lifetime.
An altered or isolated component interferes with the activity of its normal counterpart, for example by sequestering a limiting partner into a nonproductive protein complex.
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Protein–protein interaction (PPI) refers to the physical contacts between two or more protein molecules as a result of biochemical events and/or electrostatic forces. These interactions are crucial for almost every biological process in cells, including enzyme activity, signaling pathways, structural integrity, immune responses, and regulatory mechanisms. PPIs can be transient or stable and can occur in various forms, such as: 1. **Homomeric Interactions**: Involves interactions between identical proteins.