Cholecystokinin receptors or CCK receptors are a group of G-protein coupled receptors which bind the peptide hormones cholecystokinin (CCK) and gastrin.^[1] There are two different subtypes CCK_A and CCK_B which are ~50% homologous:^[2] Various cholecystokinin antagonists have been developed and are used in research, although the only drug of this class that has been widely marketed to date is the anti-ulcer drug proglumide.