To assess the red blood cell (RBC) membrane's ability to maintain normal phospholipid orientation in the face of deforming stress, we examined RBC subjected to elliptical, tank-treading deformation. As determined by accessibility to phospholipase digestion and by labeling with fluorescamine, normal RBC are able to fully preserve their phospholipid asymmetry despite attaining over 96% of their maximal possible deformation. Phospholipid orientation is unchanged during deformation even for RBC that are ATP-depleted or vamadate-treated and for RBC that already have destabilized phospholipids due to treatment with t-butyl hydroperoxide. These data indicate that maintenance of phospholipid organization during marked deforming stress and tank-treading motion of the membrane is ascribable predominantly to the passive stabilizing effect of membrane proteins. This provides additional evidence for the concept of a unit membrane characterized by intimate associations between lipid and protein.
Bibliographical noteFunding Information:
Supported by the National Institutes of Health (H1_30160 and HL37528) and the Minnesota Medical Foundation. We thank Carol Taubert for assistance in manuscript preparation.
- Erythrocyte deformation
- Erythrocyte membrane
- Phospholipid asymmetry
- Sickle cell
- t-Butyl hydroperoxide