Monitor peptide binding sites are expressed in the rat liver and small intestine

I-125-monitor peptide binding was performed using frozen sections of the ra t liver and gut and visualized using autoradiography. Saturable binding was observed in unidentified single cells in the liver and in the mucosa of th e small intestine. Epidermal growth factor (EGF) and GTP gamma S did not in hibit I-125-monitor peptide binding indicating that the binding sites are n ot EGF receptors or G protein-coupled receptors. The liver binding site exh ibited an affinity 3.7-4.4-fold higher than those in the small intestine. I t has been established that intraluminal monitor peptide releases cholecyst okinin from the small intestine. The present results indicate that monitor peptide may also have liver associated functions. (C) 1999 Elsevier Science Inc. All rights reserved.