Functional topography of band 3: specific structural alteration linked to functional aberrations in human erythrocytes.
Band 3 is the major anion transport polypeptide of erythrocytes. It appears to be the binding site of several glycolytic enzymes. Structurally, band 3 is the major protein spanning the erythrocyte membrane and connects the plasma membrane to band 2.1, which binds to the cytoskeleton. In the present study, we report an alteration of band 3 molecule that is associated with the following changes: erythrocyte shape change from discoid to "thorny cells" (acanthocytes), restriction of rotational diffusion of band 3 in the membrane, increase in anion transport, and decrease in the number of high-affinity ankyrin-binding sites. Changes in erythrocyte IgG binding, glyceraldehyde-3-phosphate dehydrogenase, fluorescence polarization (indicative of membrane fluidity), and other membrane proteins as determined by polyacrylamide gel electrophoresis were not detected. Cells containing the altered band 3 polypeptide were obtained from individuals with abnormal erythrocyte morphology. Two-dimensional peptide maps revealed differences in the Mr 17,000 anion transport segment of band 3 consistent with additions of tyrosines or tyrosine-containing peptides. The data suggest that (i) this alteration of band 3 does not result in accelerated aging as does cleavage and (ii) structural changes in the anion transport region result in alterations in anion transport.
Kay
M M
MM
Department of Medicine, Texas A & M University, Temple 76504.
Bosman
G J
GJ
Lawrence
C
C
D000050:Acanthocytes / Q000378:metabolism*; D001457:Anion Exchange Protein 1, Erythrocyte / Q000235:genetics / Q000378:metabolism; D017487:Ankyrins; D001798:Blood Proteins / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D004905:Erythrocyte Aging; D004912:Erythrocytes / Q000378:metabolism*; D004913:Erythrocytes, Abnormal / Q000378:metabolism*; D006402:Hematologic Diseases / Q000097:blood; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D010449:Peptide Mapping; D011485:Protein Binding; D011487:Protein Conformation; D012016:Reference Values
D001457:Anion Exchange Protein 1, Erythrocyte; D017487:Ankyrins; D001798:Blood Proteins; D008565:Membrane Proteins