The molecular basis of the defect in phosphorylation of spectrin in human hereditary spherocytosis.

The molecular basis for the depressed phosphorylation of the smaller polypeptide of spectrin (band 2) in the erythrocytes of patients suffering from hereditary spherocytosis is investigated. Comparison of healthy and spherocytic spectrin polypeptides by controlled proteolysis reveals no abnormality in the degradation pattern or in the sites of phosphorylation. It is concluded that the lesion is a consequence of a defective control of phosphorylation. The defect can be mimicked in healthy cells by the introduction of calcium into the erythrocyte and the possibility that the primary pathological lesion is a deficient control of the calcium content of the erythrocyte is discussed.