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Báo cáo khoa học: Insulin-dependent phosphorylation of DPP IV in liver Evidence for a role of compartmentalized c-Src
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Dipeptidyl peptidase IV (DPP IV, CD26, EC 3.4.14.5) 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 R.L. 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 robert.faure@crchul.ulaval.ca Received 16 November 2005 revised 23 December 2005 accepted 3 January 2006 doi 10.1111 j.1742-4658.2006.05125.x Dipeptidyl peptidase IV DPP IV CD26 EC 3.4.14.5 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 .