The gastrin receptor

Two CCK receptor subtypes, CCK and CCKg are known. A related receptor, the gastrin receptor, has also been described. CCK receptors predominate in the gastrointestinal tract and pancreas and are also localized in discrete brain regions. CCKg receptors predominate in the brain. A 71623... 

The gastrin receptor is one of the receptors that bind cholecystokinin (Table 13.4), and is known as the CCK-B receptor it is another member of the G-protein-coupled receptor family. 

CCK interacts with at least two types of receptor [5]. These sub-types have been designated CCK-A and CCK-B. The former is located predominantly in the periphery (gut etc.) and the latter is found in high abundance in the brain. The gastrin receptor of the stomach shares similarities with the CCK-B receptor, but can be pharmacologically distinguished from it [6]. 

In an approach to the gastrin receptor antagonist (+)-AG-041, the Iwabuchi group has prepared the nitrogen-substituted spirocycle 153 by means of an oxidative intermolecular aza-spiro-annulation (Scheme 38) [82], Accordingly, indole 151 was treated with dirhodium catalyst 152 in the presence of PHl(OAc)2 and MgO to afford spirocycle 153 in 70% yield and 96% ee. The deuterium labeling was necessary for successful implementation of the spirocyclization. 

Figure 5. A model of the receptors present on the basolateral surface of the parietal cell and their intracellular effects, which lead to movement of the H,K ATPase from the cytoplasmic tubule to the microvillus of the secretory canaliculus. The cholinergic receptor is of the M3 sub-type and increases intracellular calcium. The gastrin receptor is the CCK-B receptor and also generates calcium signaling, although it appears that elevation of cAMP is required for this signaling cascade. The histamine 2 (H2) receptor is coupled mainly to adenylate cyclase and is the major regulatory receptor for acid secretion. The substrates for the A kinase are not known.

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