What is the Origin of G Protein-Coupled Receptor?

The name is descriptive, combining the characteristic structure—a receptor—with the key intracellular effector protein—the G protein—to which it couples upon activation. The existence of these receptors was inferred from pharmacological studies, but their molecular structure and function were definitively elucidated through decades of biochemical and genetic research, culminating in Nobel Prize-winning work in the early 2000s. They represent a fundamental mechanism of signal transduction across all biological life.

What is the Mechanism of G Protein-Coupled Receptor?

The mechanism begins with the binding of an external ligand, such as a hormone, to the extracellular domain of the GPCR, which induces a conformational change in the receptor's intracellular domain. This change allows the receptor to activate an associated heterotrimeric G protein by facilitating the exchange of GDP for GTP on the G-alpha subunit. The activated G-alpha or the G-beta-gamma subunits then dissociate and initiate various downstream signaling cascades, often involving second messengers like cyclic AMP (cAMP) or inositol trisphosphate (IP3), ultimately leading to a specific cellular response.

G Protein-Coupled Receptor

Meaning

A G Protein-Coupled Receptor (GPCR) is a large, ubiquitous family of integral membrane proteins that function as cellular sensors, recognizing and responding to an immense array of extracellular signals, including many hormones, neurotransmitters, and growth factors. These receptors span the cell membrane seven times and are central to nearly all physiological processes, making them a primary target for approximately one-third of all modern pharmaceutical agents. Their function is crucial in endocrinology as they mediate the effects of many peptide and amine hormones, translating external chemical messages into internal cellular responses.