G-Protein Coupled Receptors (GPCRs) segmentation by application maps demand to therapeutic area value, with oncology leading at 34% of 2023 market revenue, driven by druggability of GPR20, CXCR4, and PAR1 in solid tumours. Cardiovascular (21%) follows, where β-blockers and AT1R antagonists are standard-of-care, guaranteeing stable replacement demand. CNS indications (19%) are the fastest-growing slice, propelled by rising investment in GPR139, TAAR1, and OXER1 for psychiatric and neurodegenerative disorders. Metabolic (12%) and respiratory (8%) complete the clinical space, while the residual 6% covers emerging areas such as ophthalmology, rare diseases, and gut-brain axis targets, collectively illustrating how therapeutic breadth underwrites the overall G-Protein Coupled Receptors (GPCRs) market size.