Organisation de la membrane de la bordure en brosse de l'intestin en rafts lipidique - caractérisation protéomique

Abstract

To assess intestinal lipid rafts functions through the characterization of their protein markers, we have isolated lipid rafts of rat mucosa either from the total membrane or purified brush border membrane (BBM) by sucrose gradient fractionation after detergent treatment. In both membrane preparations, the floating fractions (4-5) were enriched in cholesterol, ganglioside GM1, and N aminopeptidase (NAP) known as intestinal lipid rafts markers. Based on MALDI-TOF/MS identification and simultaneous detection by immunoblotting, 12 proteins from the BBM cleared from contaminants were selected as rafts markers. These proteins include several signaling/trafficking proteins belonging to the G-protein family and the annexins as well as glycosylphosphatidylinositol (GPI)-anchored proteins. Remarkably GP2, previously described as the pancreatic granule GPI-anchored protein, was found in intestinal lipid rafts. The proteomic strategy assayed on the intestine leads to the characterization of known (NAP, alkaline phosphatase, dipeptidyl aminopeptidase, annexin II, and galectin-4) and new (GP2, annexins IV and XIIIb, Gaq, Ga11, glutamate receptor, and GPCR 7) lipid rafts protein markers. Together our results indicate that some digestive enzymes, trafficking and signaling proteins may be functionally distributed in the intestinal lipid rafts.AIX-MARSEILLE3-BU Sc.St Jérô (130552102) / SudocSudocFranceF