THE ROLE OF SPECTRIN AND ACTIN IN IRREVERSIBLY SICKLED CELLS: UNSICKLING OF “IRREVERSIBLY” SICKLED GHOSTS BY CONDITIONS WHICH INTERFERE WITH SPECTRIN-ACTIN POLYMERIZATION

Abstract

We have previously shown that irreversibly sickled cells (ISCs) form ISC-shaped ghosts and ISC-shaped membrane skeletons which suggests that an alteration in the membrane skeleton of the ISC may be responsible for its abnormal shape. In the present studies we observe that ISC-shaped ghosts become round in hypertonic media (>400 mM NaCl), hypotonic media (10 to 50 mM NaCl), and isotonic NaCl containing small amounts of Zn 2+ (0.1 to 0.5 mM). This ISC-shape reversal is time and temperature dependent and does not correlate with the elution or proteolysis of any membrane protein(s) detectable on SDS-gels. Conditions which promote ISC ghosts reversal also inhibit the formation of spectrin-actin complex(es). This suggests that ISCs may be stabilized by abnormal interactions between the spectrin and/or actin components of the membrane skeleton and that disruption of these bonds may allow the skeleton to resume a normal shape.