tailieunhanh - Báo cáo khoa học: Insulin-dependent phosphorylation of DPP IV in liver Evidence for a role of compartmentalized c-Src

Dipeptidyl peptidase IV (DPP IV, CD26, EC ) serves as a model aimed at elucidating protein sorting signals. We identify here, by MS, sev-eral tyrosine-phosphorylated proteins in a rat liver Golgi⁄endosome (G⁄E) fraction including DPP IV. We show that a pool of DPP IV is tyrosine-phosphorylated. | iFEBS Journal Insulin-dependent phosphorylation of DPP IV in liver Evidence for a role of compartmentalized c-Src Nicolas Bilodeau1 Annie Fiset1 Guy G. Poirier2 Suzanne Fortier1 Marie-Claude Gingras3 Josee N. Lavoie3 and Robert L. Faure1 1 Pediatric Research Unit CRCHUL CHUQ Faculty of Medicine LavalUniversity Quebec Canada 2 Quebec Proteomic Center CRCHUL CHUQ Faculty of Medicine LavalUniversity Quebec Canada 3 Cancer Research Center CRHDQ CHUQ Faculty of Medicine LavalUniversity Quebec Canada Keywords c-Src DPP IV endosomes tyrosine phosphorylation subcellular fractionation Correspondence . Faure Pediatric Research Unit Cell Biology Laboratory Room 9800 CHUL MedicalResearch Center 2705 Laurier Boulevard Quebec QC G1V 4G2 Canada Fax 1 418 654 2753 Tel 1 418 656 4141 extn 48263 E-mail Received 16 November 2005 revised 23 December 2005 accepted 3 January 2006 doi Dipeptidyl peptidase IV DPP IV CD26 EC serves as a model aimed at elucidating protein sorting signals. We identify here by MS several tyrosine-phosphorylated proteins in a rat liver Golgi endosome G E fraction including DPP IV. We show that a pool of DPP IV is tyrosine-phosphorylated. Maximal phosphorylation was observed after 2 min following intravenous insulin injection. DPP IV coimmunoprecipitated with the cellular tyrosine kinase Src c-Src with maximal association also observed after 2 min following insulin injection. DPP IV was found phosphorylated after incubation of nonsolubilized G E membranes with y-32P ATP. The c-Src inhibitor PP2 inhibited DPP IV phosphorylation. Oriented proteolysis experiments indicate that a large pool of c-Src is protected in G E fractions. Following injection of the protein-tyrosine phosphatase inhibitor bpV phen DPP IV levels markedly decreased by 40 both in plasma membrane and G E fractions. In the fraction designated Lh DPP IV levels decreased by 50 15 min following insulin injection. Therefore a .