[The mechanism of anti-insulin effect of apoprotein B].

The existence of common epitope in insulin molecule and apolipoprotein B one was shown by means of enzyme immunoassay. Similar epitopes were revealed in apoB-containing lipoproteins (VLDL and LDL) by dot-immunobinding and immunoelectroblotting. Epitopes locate on the surface of lipoproteins and are not screened by lipids. The existence of common epitopes is the reason of competition between insulin and LDL. The experiments with isolated perfused rat hindquarter demonstrate that insulin increased the glucose uptake by muscle and LDL decreased it. Simultaneous perfusion with LDL and insulin leads to reduced insulin action due to completion for insulin receptors. After the recovery of S-S bounds apoB forms some proteins, containing common epitopes with insulin. The presence of such proteins was shown in lipoprotein-free serum. Apoprotein B and its derivates seem to be insulin antagonists with marked antiinsulin action.