GPR45 is an orphan G protein-coupled receptor located on chromosome 2.1-q12 that plays a role in brain function and energy homeostasis 1. It is predominantly expressed in the central nervous system, including olfactory mitral cells, cortical neurons, hippocampal pyramidal cells, and cerebellar Purkinje cells 2. GPR45 represents a mammalian orthologue of a putative lysophosphatidic acid receptor from Xenopus laevis 1 and belongs to a distinct GPCR family with unique sequence characteristics 2. GPR45 localizes to neuronal cilia and exerts regulatory effects on energy balance and satiety through spatial compartmentalization of metabolic signaling 3. Genome-wide association studies have identified GPR45 variants as associated with obesity susceptibility and type 2 diabetes mellitus risk in diverse populations 43. Additionally, GPR45 shows significant genetic association with age at menarche in females, suggesting involvement in sexual maturation pathways 5. During erythroid differentiation, GPR45 expression is particularly prominent in fetal liver-derived progenitor cells 6. Despite its identification as an orphan receptor, GPR45's ciliary localization and association with metabolic and developmental phenotypes indicate functional importance in neuroendocrine regulation.