Intra- and intermolecular cross-linking of membrane proteins in intact erythrocytes and ghosts by SH-oxidizing agents.

In intact human erythrocytes, SH-oxidizing agents exclusively cross-link spectrin via disulfide bonds. In ghosts, additional dimerization of the major intrinsic protein, band 3, is observed. After blockade of intracellular GSH the agents dimerize band 3 in the intact cell too, indicating that GSH may prevent band 3 dimerization under physiological conditions. The oxidizing agents reversibly oxidize 80% of the membrane SH-groups, suggesting that these groups are arranged close enough to each other to form disulfide bonds. This arrangement may protect other cell cell structures against free radicals or oxidative stress.