RTP2 (receptor transporter protein 2) is a transmembrane accessory protein that promotes functional cell surface expression of olfactory receptors (ORs) 1. RTP2 is expressed specifically in olfactory sensory neurons and facilitates OR trafficking to the plasma membrane, enabling ligand-induced receptor responses 2. Unlike its closely related family member RTP1S, which robustly supports odorant-mediated responses across diverse ORs, RTP2 exhibits more selective and nuanced effects 3. When tested with 24 ORs against 28 cognate ligands, RTP2 showed little functional enhancement and even suppressive effects on certain OR responses, while increasing detection thresholds for some receptors 3. Protein-protein interaction studies confirm that RTP2 associates with both ORs and RTP1S, and immunocytochemical analyses reveal that RTP2 co-expression affects OR trafficking dynamics, causing retention of OR and RTP1S in the Golgi apparatus 3. Beyond olfaction, RTP2 expression has been detected in central nervous system neurons, where its function remains unclear 4. The divergent roles of RTP1S and RTP2 suggest distinct mechanisms for regulating functional OR expression, with potential implications for understanding olfactory signal transduction and possibly broader chemosensory processing in the brain.