AN INSULIN-RESPONSE ELEMENT IN THE GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE GENE BINDS A NUCLEAR-PROTEIN INDUCED BY INSULIN IN CULTURED-CELLS AND BY NUTRITIONAL MANIPULATIONS INVIVO

Two independent distracting insulin response elements (IREs) in the gene encoding glyceraldehyde-3-phosphate dehydrogenase [D-glyceraldehyde-3-phosphate : NAD+ oxidoreductase (phosphorylating), EC 1.2.1.12], designated IRE-A and IRE-B, are sufficient to direct insulin-inducible gene expression. Using the electrophoretic mobility shift assay, a 4-fold increase in the amount of IRE-A DNA bound to nuclear proteins was detected when extracts isolated from insulin-stimulated differentiated 3T3-L1 cells or from the liver of rats refed a high-carbohydrate/low-fat diet after a 72-hr fast were compared to control nuclear extracts. The points of contact between protein and IRE-A DNA may represent a sequence recognized by at least one class of insulin-sensitive transcription factor(s). (.