Receptors for gastrin on gastric carcinoid tumor membrane of Mastomys natalensis.

Abstract

Specific binding sites for human gastrin I (gastrin) were identified in a crude membrane preparation from the gastric carcinoid tumor of Mastomys (Praomys) natalensis. The binding of 125I-gastrin to the carcinoid tumor membrane was saturable, and Scatchard analysis of the data revealed a single class of binding site with a dissociation constant of 139.2 pM and a maximal binding capacity of 23.5 fmol/mg protein. Gastrin and CCK8 equipotently and dose-dependently displaced the binding of 125I-gastrin to the membrane. GTP but not ATP decreased 125I-gastrin binding to the membrane, and removal of Mg2+ attenuated this inhibitory action of GTP. The GTP-induced reduction of 125I-gastrin binding was found to be due to a decrease in binding affinity without a change in binding capacity. These results clearly indicate the presence of specific binding sites for gastrin, probably coupled to guanine nucleotide-binding protein, in the carcinoid tumor membrane of Mastomys, and suggest that gastrin has possible biological actions on these tumors.

• Authors: T Chiba, Y Kinoshita, T Morishita, H Nakata, A Nakamura, S Hosoda
• Journal: Biochemical and biophysical research communications (Biochem Biophys Res Commun) Vol. 177 Issue 2 Pg. 739-44 (Jun 14 1991) ISSN: 0006-291X [Print] United States
• PMID: 2049096 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Gastrins
• Receptors, Cholecystokinin
• Guanosine Triphosphate
• Adenosine Triphosphate

Topics

• Adenosine Triphosphate (pharmacology)
• Animals
• Carcinoid Tumor (chemistry, metabolism)
• Cell Membrane (chemistry, metabolism)
• Female
• Gastrins (metabolism)
• Guanosine Triphosphate (pharmacology)
• Humans
• Kinetics
• Muridae
• Receptors, Cholecystokinin (analysis, drug effects)
• Stomach Neoplasms (chemistry, metabolism)