Figure 3
Alteration of the rbc membrane by polymers of sickle hemoglobin.
Deoxygenation of Hb S induces a change in conformation in which the mutant β chain binds to a complementary hydrophobic site resulting from a valine replacement, leading to the formation of a hemoglobin polymer (Hb polymer; lower right, inset). The hemoglobin polymers disrupt the rbc cytoskeleton and form protrusions, giving rise to the characteristic sickle appearance. Interruption of the attachment of the membrane to the protein cytoskeleton results in exposure of transmembrane protein epitopes and lipid exchanges, notably of phosphatidylserine (PS), between the inside and the outside of the cell (upper right, inset). Exposure of negatively charged glycolipids contributes to the proinflammatory and prothrombotic state of sickle cell blood. Adapted with permission from Blackwell Publishing (129).
