What are the five groups in the GPCR family?

The five groups of the G protein-coupled receptor (GPCR) family are Class A (rhodopsin-like), Class B (secretin-like), Class C (metabotropic glutamate/pheromone), Class D (fungal mating pheromone), and Class E (cyclic nucleotide). Class A receptors are the largest group and are involved in various physiological processes. Class B receptors primarily bind peptide hormones, while Class C receptors often interact with neurotransmitters and modulators. Classes D and E are more specialized, with Class D found mainly in fungi and Class E associated with specific signaling pathways.