A molecular defect in two families with hemolytic poikilocytic anemia: reduction of high affinity membrane binding sites for ankyrin

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Title: A molecular defect in two families with hemolytic poikilocytic anemia: reduction of high affinity membrane binding sites for ankyrin
Author: Bennet, V; Chui, D H; Orringer, E P; Agre, P
Abstract: Patients from two families with chronic hemolytic anemia have been studied. The erythrocytes are very fragile and appear microcytic with a great variety of shapes. Clinical evaluation failed to identify traditionally recognized causes of hemolysis. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed no significant abnormality of the major polypeptide bands. Erythrocytes spectrin-ankyrin and ankyrin-membrane interactions were analyzed with 125I-labeled spectrin, 125I-labeled ankyrin, and inside-out vesicles. Patients' vesicles bound 125I-spectrin normally. Likewise, patients' spectrin and ankyrin competed normally for the binding sites on control membranes. None of the individual components appeared to have abnormal thermal sensitivity. Ankyrin-stripped, inside-out vesicles prepared from the patients bound less 125I-ankyrin than did vesicles prepared from normals (P less than 0.05 for all corresponding points in the high-affinity region). Scatchard analysis showed the most significant abnormality to be a 50% reduction in the high affinity ankyrin binding sites. Similar experiments were performed with blood from patients with spherocytosis and splenectomized controls, but no abnormalities were detected. The water soluble 43,000-dalton fragments of band 3 (the high-affinity ankyrin binding sites) were prepared from one of the patients and competed normally for 125I-ankyrin binding in solution. This suggests that the primary structural defect is a reduction in the number of high affinity membrane binding sites for ankyrin, and is consistent with an abnormal organization of band 3 in the membrane.
URI: http://jhir.library.jhu.edu/handle/1774.2/33789
Date: 1981-12
Citation: J Clin Invest. 1981 December; 68(6): 1566–1576. doi: 10.1172/JCI110411
Subject: Membrane Proteins/metabolism
Erythrocytes, Abnormal/metabolism
Cell Membrane/metabolism
Anemia, Hemolytic/blood

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