G protein-coupled receptors (GPCRs) are plasma membrane proteins that act as sensors for extracellular stimuli (e.g., photons, neurohumoral moduluators, odorants and tastants, lipids). The cognate stimulus for a GPCR induces a
conformational change that catalyzes, via
heterotrimeric G proteins, a series of biochemical reactions inside the cell (i.e., a response); the responses can lead to phenomena such as differentiation, morphological changes, chemotaxis, and mitosis. G protein-coupled receptors are the targets of, in addition to endogenous neurohumoral molecules, more than 30% of currently marketed pharmaceutical drugs. For instance, the effective appetite suppressant fenfluramine reduces…
