[Oligomerization of integral membrane proteins under lipid peroxidation]

Using polyacrylamide gel electrophoresis in the presence of Na-SDS, the oligomerization of membrane proteins of the retinal rod outer segments of the frog and the wall-eyed pollock and of rabbit skeletal muscle sarcoplasmic reticulum was studied. It was shown that under storage of the retinal rod outer segments the rhodopsin oligomerization is inhibited by the lipid peroxidation inhibitor--ionol. Similar oligomerization was observed under induction of lipid peroxidation in the membranes; the accumulation of the lipid peroxidation product--malonic dialdehyde--was accompanied by disappearance of the rhodopsin monomeric form in the outer segments. The cross-linking agent--glutaric dialdehyde--also causes oligomerization of the rhodopsins. Similar aggregation is also characteristic of the major protein of the sarcoplasmic reticulum fragments, i. e. Ca2+-dependent ATP-ase. Thus, one of the main changes in the protein content of biomembranes under lipid peroxidation is the oligomerization of integral proteins due to their interaction with bifunctional reagents, i. e. lipid peroxidation products.