Membrane protein lesions in erythrocytes with Heinz bodies.

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Abstract

We studied Heinz body-containing erythrocytes with three different unstable hemoglobins: Nottingham, Brockton, and unclassified. We demonstrated two classes of membrane protein defects in unstable hemoglobin-containing cells (UH-RBCs), a defect of the spectrin-depleted inside-out vesicle (UH-IOV), and a defect of spectrin (UH-spectrin) itself. The composition of UH-IOVs is the same as control with respect to quantity of ankyrin and proportion inside-out. However, UH-IOVs bind even less spectrin than IOVs derived from sickle erythrocytes (SS-IOVs), suggesting a severe functional defect in the ankyrin of UH-RBCs (UH-ankyrin). Further evidence that UH-ankyrin is abnormal is demonstrated by the virtual absence of ankyrin in isotonic membrane shells of UH-RBCs (UH-shells), and abnormal mobility and decreased binding of the 72-kD (spectrin-binding) alpha-chymotryptic fragment of UH-ankyrin (UH-72-kD) to control spectrin. All UH-RBC membranes were spectrin-deficient (60% of control). In addition, spectrin isolated from UH-RBCs (UH-spectrin) was abnormal in two respects: (a) presence of a fast-moving band on nondenaturing polyacrylamide gels of both 0 degree C and 37 degrees C extracts, and (b) decreased binding to actin in the presence of protein 4.1. UH-spectrin did exhibit normal self-association, binding to IOVs and binding to actin in the absence of protein 4.1. This pattern of normal and abnormal spectrin functions has been described for spectrin subjected to mild diamide oxidation, suggesting the role of oxidation is the pathogenesis of membrane defect(s) of erythrocytes with abnormal hemoglobins.

Authors

O S Platt, J F Falcone