The Mouse Intestinal Fatty Acid Binding Protein Gene: Nucleotide Sequence, Pattern of Developmental and Regional Expression, and Proposed Structure of Its Protein Product
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The rat intestinal fatty acid binding protein (I-FABP) gene has been used as a model to study temporal and spatial differentiation of the gut epithelium while its protein product has been used as a model for examining the atomic details of noncovalent fatty acid-protein interactions. We have isolated the mouse I-FABP gene (Fabpi) and determined its nucleotide sequence. Comparisons of the orthologous mouse, rat, and human I-FABP genes revealed three conserved domains in their otherwise divergent 5' nontranscribed sequences. RNA blot hybridization and multilabel immunocytochemical methods were used to compare the developmental stage-specific patterns of activation of the rat and mouse genes. In addition, Fabpi expression in enterocytes was examined as a function of their differentiation along the crypto-to-villus and duodenal-to-colonic axes of the small intestine. Based on the similar temporal and geographic patterns of mouse and rat I-FABP expression described here and the results of our earlier studies of transgenic mice containing rat Fabpi/human growth hormone fusion genes, we propose that one of the conserved domains, spanning nucleotides -500 to -419 in mouse Fabpi, and/or a 14-bp element, are necessary for establishing and maintaining its region-specific expression along the duodenal-to-colonic axis of the perpetually renewing gut epithelium. Finally, predictions of the structure of mouse I-FABP using the refined 2.0 A model of rat I-FABP, suggest that a proline found at position 69 of the mouse, but not rat, protein may affect its ligand binding properties.
author list (cited authors)
Green, R. P., Cohn, S. M., Sacchettini, J. C., Jackson, K. E., & Gordon, J. I.