Widespread tissue expression of gastrin-binding-protein mRNA

Glycine-extended forms of gastrin (gastrin-Gly) are thought to be involved in the autocrine growth control of colorectal carcinomas. The recently described gastrin-binding protein has been suggested to be a gastrin-Gly accepting receptor. Northern blot analysis demonstrated the expression of gastrin-binding-protein mRNA in many tissues of mouse, rat, and man. The gastrin-binding-protein mRNA expression was confirmed by reverse-transcribed PCR analysis. Analysis of the cDNA and the deduced amino acid sequence of the PCR-amplified rat gastrin-binding-protein DNA fragments revealed sequence identity (except in a single position) with the corresponding human and pig gastrin-binding protein and with the alpha-subunit of a rat and human mitochondrial trifunctional enzyme, involved in fatty acid oxidation. The widespread and abundant tissue expression of gastrin-binding-protein mRNA and its sequence identity with a fatty-acid-oxidizing enzyme do not support the view that it represents a genuine gastrin receptor.