INSULIN-DEPENDENT TRANSLOCATION OF THE SMALL GTP-BINDING PROTEIN RAB3C IN CARDIAC-MUSCLE - STUDIES ON INSULIN-RESISTANT ZUCKER RATS

The failure of insulin-regulated recruitment of the GLUT4 glucose tran sporter in cardiac muscle of obese Zucker rats is associated with alte rations of the subcellular distribution of the small-molecular-mass GT P-binding protein rab4A, Here, me show by subcellular fractionation an d Western blotting a translocation of the small-molecular-mass GTP-bin ding protein rab3C from microsomal membranes to plasma membranes in le an control rats following in vivo insulin stimulation, However, in car diac muscle of obese animals no significant effect of the hormone on t he subcellular distribution of rab3C was observed, In GLUT4-enriched m embrane vesicles, obtained from cardiac microsomes of the obese group as well as of lean controls, rab3C mas not detectable. It is suggested that the altered behaviour of rab3C may contribute to an impaired tra fficking of GLUT4 in the insulin-resistant state.