Mammalian odorant receptors require accessory proteins such as RTP1 and RTP2 for functional cell surface expression. Receptor expression-enhancing protein (REEP) family members are transmembrane proteins which interact with odorant receptor proteins and may enhance the odorant receptor responses to odorants. Recently studies have shown other chemosensory receptors such as bitter taste receptors are also influenced by RTP and REEP family members. In studies in Xenopus RNAi to reduce REEP4 levels, embryos showed a slightly kinked body axis and were paralyzed. Further analysis revealed downregulated levels of several neural and muscle markers, suggesting the REEP4 may play a role in the maintenance of both the nervous system and musculature.