Cholecystokinin B receptor (CCKBR/CCK2R) is a 447-amino acid 7 transmembrane protein. The cholecystokinin (CCK) family of peptides and their receptors are widely distributed throughout the central nervous system and gastrointestinal tract. CCKBR is a type B (gastrin) receptor that has high affinity for both sulfated and nonsulfated CCK analogs found principally in the CNS and select areas of the gastrointestinal tract. Type B receptors regulate anxiety, arousal, neuroleptic activity and opiate-induced analgesia. Outside of the CNS they regulate gastric acid secretion and may play a role in gastrointestinal motility and growth of normal and neoplastic gastrointestinal tissue. Northern hybridization shows CCKBR expressed in the stomach, pancreas, brain and gallbladder.