Proteincoupled

Proteincoupled is a descriptor used in biochemistry and cell biology to denote systems in which proteins mediate the coupling of one event to another, such as signal initiation to cellular response, or the linkage of energy transduction to function. In most biological contexts, protein coupling involves physical interactions that transfer information from one protein to another, often triggered by ligand binding or post-translational modification. The interactions are typically mediated by defined protein domains and can be modulated by cellular context, localization, and expression levels.

A central example is protein-coupled receptors (GPCRs), where binding of an extracellular ligand induces a conformational change that enables coupling to intracellular signaling proteins like heterotrimeric G proteins, leading to activation of second messengers such as cAMP or IP3/DAG, and downstream effects. Other forms include kinases that are activated by phosphorylation events, adaptor proteins that assemble signaling complexes, and enzymes that are regulated by substrate binding through allosteric coupling. The concept also encompasses non-membrane contexts, such as metabolic enzyme coupling and protein–protein interaction networks that coordinate cellular processes. Studying proteincoupled interactions helps explain specificity in signaling, robustness of responses, and how dysregulation contributes to disease. Therapeutic strategies often target protein coupling interfaces or the binding between receptors and effector proteins to modulate signaling.