Ubiquitination of erythrocyte spectrin regulates the dissociation of the spectrin-adducin-f-actin ternary complex in vitro.

We demonstrate that ubiquitinated red blood cell (RBC) spectrin dissociates more rapidly from the spectrin-adducin-actin ternary complex, than non-ubiquitinated spectrin. Homozygous (SS) sickle cell spectrin has substantially diminished ubiquitination of alpha-spectrin resulting in slower dissociation from the spectrin-adducin-actin ternary complex, than normal (AA) cell spectrin. These results supply a partial explanation of the slow dissociation of the irreversible sickle cell (ISC) membrane skeleton, which leads to the inability of the ISC to change shape.