ISOLATION OF INSULIN RECEPTOR PHOSPHATASES

THE ULTIMATE OBJECTIVE OF THIS RESEARCH IS TO DEVELOP A NOVEL TREATMENT FOR DIABETES BASED ON THE ENHANCEMENT OF INSULIN ACTION THROUGH THE INHIBITION OF AN INSULIN RECEPTOR-SPECIFIC PHOSPHOTYROSINE PHOSPHATASE (PTPASE). PHOSPHORYLATION OF THE INSULIN RECEPTOR BETA-SUBUNIT, IN RESPONSE TO INSULI BINDING, HAS BEEN CORRELATED WITH ACTIVATION OF THE PLEIOTROPHIC INTRA- CELLULAR INSULIN SIGNAL. MODULATION OF THE PHOSPHORYLATION STATE OF THE INSULIN RECEPTOR COULD AFFECT POST-RECEPTOR SIGNALLING EVENTS. THE SPECIFIC AIMS OF THIS PROJECT ARE TO IDENTIFY AND PURIFY AS INSULIN RECEPTOR PTPASE(S). DURING PHASE I, WE WILL IDENTIFY AND PARTIALLY PURIFY AN INSULIN RECEPTOR-SPECIFIC PTPASE. THE SPECIFICITY OF THE PHOSPHATASE WILL BE EXAMINED COMPARING DEPHOSPHORYLATION OF THE INSULIN RECEPTOR TO OTHER PHOSPHOTYROSINE, PHOSPHOSERINE, AND PHOSPHOTHREONINE-CONTAINING SUBSTRATES. DURING PHASE II, WE WILL CONTINUE PURIFICATION, GENERATE MONOCLONAL ANTIBODIES, AND IDENTIFY THE CDNA ENCODING THE INSULIN RECEPTOR PTPASE ACTIVITY.