HCRTR2 encodes hypocretin receptor 2, a G protein-coupled receptor that binds the neuropeptides orexin-A and orexin-B with high affinity. Through this binding, it activates G(q)/11 and G(i)/o signaling to modulate cytoplasmic Ca2+ levels and neuronal excitability, placing it at the center of sleep-wake cycle regulation and central glucose homeostasis. Protein expression is high in the brain, consistent with its role in neural control of arousal and metabolism.