EFFECT OF CATIONS ON THE TYROSINE KINASE ACTIVITY OF THE INSULIN RECEPTOR : INHIBITION BY FLUORIDE IS MAGNESIUM DEPENDENT

摘要: We have recently reported that fluoride interacts directly with the insulin receptor, which causes inhibition of its phosphotransferase activity. The inhibitory effect on activity is not due to formation complexes aluminium and occurs in absence alterations binding ATP or insulin. In this report we substantiate tyrosine kinase receptors partially purified from rat skeletal muscle shows a strict requirement Mg2+ ions (Ka near 11 mM). This was inhibited competitive manner by Mn2+, compatible competition both divalent for sites. caused dependent concentration medium no detected at low concentrations Mg2+. Moreover, addition increasing Mn2+ presence constant high concentr rease fluoride. These results indicate Mg-insulin receptor complex major fluoride-susceptible form. Based characteristics shown it might be proposed action exerted multi-ionic MgF analogous Pi, bind kinase.