VIPR1 (Vasoactive Intestinal Peptide Receptor 1): VIPR1 is a receptor that binds vasoactive intestinal peptide (VIP), a neuropeptide involved in diverse physiological processes such as smooth muscle relaxation, immune system regulation, and water and ion transport in the lungs. It also contributes to circadian rhythm regulation and is linked to conditions including asthma and pulmonary hypertension.