The human GPCR family is classified into subclasses A (rhodopsin-like), B (secretin and adhesion), C (glutamate), and F (Frizzled) based on their amino acid sequences. Class A GPCRs, a family of rhodopsin-like receptors consisting of 719 members, are further divided into several subclasses: amines, peptides, proteins, lipids, melatonin, nucleotides, steroids, saccharocarboxylic acids, sensory receptors, and orphan receptors. Indications for Class A GPCRs include pain relief, allergies, cardiovascular diseases, hypertension, and cancer.
