GPR39 (G Protein-Coupled Receptor 39) is a class A G protein-coupled receptor (GPCR) belonging to the ghrelin receptor family. Initially considered an orphan receptor, it was later identified as a zinc-sensing receptor activated by extracellular Zn²⁺ ions, though its endogenous ligand(s) remain under investigation. GPR39 is widely expressed in tissues such as the gastrointestinal tract, pancreas, thyroid, brain, and immune cells, suggesting roles in diverse physiological processes. It signals primarily through Gαq/11 and Gα12/13 proteins, regulating pathways like IP3-Ca²⁺, MAPK, and RhoA, which influence cell proliferation, apoptosis, and metabolism.
Research highlights GPR39's involvement in metabolic regulation (e.g., insulin secretion, glucose homeostasis), neuroprotection, and immune modulation. Dysregulation is linked to disorders including diabetes, obesity, depression, and cancer. Antibodies targeting GPR39 are essential tools for studying its expression, localization, and function. They enable techniques like Western blotting, immunohistochemistry, and flow cytometry, aiding in mapping tissue distribution and signaling mechanisms. Commercially available antibodies often target extracellular or intracellular epitopes, with validation required for species cross-reactivity (human, mouse, rat) and assay-specific performance. Recent studies also explore therapeutic potential, such as GPR39 agonists for metabolic syndrome. However, challenges persist, including antibody specificity issues and incomplete understanding of receptor activation pathways, underscoring the need for continued research.