GPR55. a G protein-coupled receptor (GPCR), was initially identified as an orphan receptor due to its structural divergence from classical cannabinoid receptors (CB1 and CB2). Emerging evidence suggests it interacts with endogenous lipid mediators, including lysophosphatidylinositol (LPI), and exhibits partial overlap with cannabinoid ligands, positioning it as a potential "third cannabinoid receptor." GPR55 is implicated in diverse physiological processes, such as inflammation, neuroprotection, bone remodeling, and metabolic regulation, with roles in pathological conditions like cancer, neurodegenerative diseases, and diabetes.
GPR55 antibodies are critical tools for elucidating its expression, localization, and function. Polyclonal and monoclonal antibodies target specific epitopes (e.g., extracellular loops or C-terminal domains) to enable applications like Western blotting, immunohistochemistry, and flow cytometry. However, antibody specificity remains a challenge due to sequence homology with other GPCRs and splice variants. Validated antibodies are essential for distinguishing GPR55 from off-target proteins in tissues such as the brain, immune cells, and gut.
Research using GPR55 antibodies has revealed its tissue-specific signaling pathways (e.g., RhoA/ROCK activation) and crosstalk with cannabinoid systems. These tools also support drug discovery efforts, as GPR55 is explored as a therapeutic target for pain, osteoporosis, and metabolic disorders. Ongoing studies aim to refine antibody reliability and expand their utility in both basic research and clinical diagnostics.