What common property do cholecystokinin and gastrin share?

Cholecystokinin (CCK) and gastrin share a common property of having structural similarities in their amino acid sequence, particularly at their C-terminal ends. Both hormones indeed exhibit five identical C-terminal amino acids, which reflects a structural homology that can play a role in their function and receptor interactions. This similarity indicates a degree of evolutionary conservation and may affect how these hormones are recognized by their respective receptors in the digestive system, influencing digestive processes.

The other options describe properties that are not applicable to both hormones. For instance, while gastrin is secreted by G cells in the stomach and plays a role in stimulating gastric acid secretion, CCK is primarily produced in the small intestine and is more involved in the digestion of fats and proteins, as well as stimulating gallbladder contraction and pancreatic enzyme secretion. Although both hormones have roles in the digestive system, only gastrin directly stimulates gastric acid secretion, whereas CCK promotes the release of digestive enzymes rather than amylase specifically. Additionally, regarding pancreatic amylase secretion and the role in gastric motility, these aspects are not a shared characteristic of both hormones. Hence, the best choice aligns with their structural similarity in the C-terminal sequence.