Release of spectrin-containing vesicles from human erythrocyte ghosts by dimyristoylphosphatidylcholine.

Membrane vesicles, which were released from human erythrocyte ghosts by dimyristoylphosphatidylcholine (DMPC), showed a protein composition similar to that of the erythrocyte membrane, despite a reduction of in spectrin content. The spectrin content of vesicles decreased with increasing hemoglobin concentration within ghost membranes, but increased upon exposure of hemoglobin-free ghosts to a pressure of 100 MPa. The ESR spectra of spin-labeled membrane proteins showed that membrane proteins in ghosts became unfolded at high pressure. Furthermore, spectrin-poor and protein 4.1-rich vesicles were released by DMPC from diamide-treated ghosts in which spectrin was cross-linked and stabilized. Taking into account that the spectrin tetramer is stabilized by hemoglobin [Liu and Palek (1984) J. Biol. Chem. 259, 11556-11562], these results suggest that the spectrin content of DMPC-induced vesicles from erythrocyte ghosts increases with increasing instability of the cytoskeletal network in parent cells.