The N-terminal Region of the Transmembrane Domain of Human Erythrocyte Band 3
We studied the role of the N-terminal region of the transmembrane domain of the human erythrocyte anion exchanger (band 3; residues 361â408) in the insertion, folding, and assembly of the first transmembrane span (TM1) to give rise to a transport-active molecule. We focused on the sequence around...
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Published in | The Journal of biological chemistry Vol. 278; no. 8; pp. 5564 - 5573 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
American Society for Biochemistry and Molecular Biology
01.02.2003
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Online Access | Get full text |
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Summary: | We studied the role of the N-terminal region of the transmembrane domain of the human erythrocyte anion exchanger (band 3;
residues 361â408) in the insertion, folding, and assembly of the first transmembrane span (TM1) to give rise to a transport-active
molecule. We focused on the sequence around the 9-amino acid region deleted in Southeast Asian ovalocytosis (Ala-400 to Ala-408),
which gives rise to nonfunctional band 3, and also on the portion of the protein N-terminal to the transmembrane domain (amino
acids 361â396). We examined the effects of mutations in these regions on endoplasmic reticulum insertion (using cell-free
translation), chloride transport, and cell-surface movement in Xenopus oocytes. We found that the hydrophobic length of TM1 was critical for membrane insertion and that formation of a transport-active
structure also depended on the presence of specific amino acid sequences in TM1. Deletions of 2 or 3 amino acids including
Pro-403 retained transport activity provided that a polar residue was located 2 or 3 amino acids on the C-terminal side of
Asp-399. Finally, deletion of the cytoplasmic surface sequence G 381 LVRD abolished chloride transport, but not surface expression, indicating that this sequence makes an essential structural
contribution to the anion transport site of band 3. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M211662200 |