Receptor for gastrin and cholecystokinin. The CCK-B receptors occur throughout the central nervous system where they modulate anxiety, analgesia, arousal, and neuroleptic activity. This receptor mediates its action by association with G proteins that activate a phosphatidylinositol-calcium second messenger system. Isoform 2 is constitutively activated and may regulate cancer cell proliferation via a gastrin-independent mechanism. Isoform 1 is expressed in brain, pancreas, stomach, the colon cancer cell line LoVo and the T-lymphoblastoma Jurkat, but not in heart, placenta, liver, lung, skeletal muscle, kidney or the stomach cancer cell line AGS. Expressed at high levels in the small cell lung cancer cell line NCI-H510, at lower levels in NCI-H345, NCI-H69 and GLC-28 cell lines, not expressed in GLC-19 cell line. Within the stomach, expressed at high levels in the mucosa of the gastric fundus and at low levels in the antrum and duodenum. Isoform 2 is present in pancreatic cancer cells and colorectal cancer cells, but not in normal pancreas or colonic mucosa. Isoform 3 is expressed in brain, pancreas, stomach, the stomach cancer cell line AGS and the colon cancer cell line LoVo. Belongs to the G-protein coupled receptor 1 family. Cholecystokinin receptor entry