In mammals, the Bombesin receptor family, belonging to the G-protein coupled receptors superfamily, includes three members: BB₁ – the neuromedin B receptor, BB₂ – the gastrin-releasing peptide receptor, and BB₃ – the orphan receptor bombesin receptor subtype 3. All three receptors are broadly expressed in the central nervous system and in the gastrointestinal tract. Activation of these receptors by their respective substrates, regulates various physiological events ranging from circadian rhythm, food intake, behavioral effects and more.