An 11-amino acid β-hairpin loop in the cytoplasmic domain of band 3 is responsible for ankyrin binding in mouse erythrocytes

Stefanovic, Marko; Markham, Nicholas O.; Parry, Erin M.; Garrett-Beal, Lisa; Cline, Amanda P.; Gallagher, Patrick G.; Low, Philip S.; Bodine, David M.

doi:10.1073/pnas.0706266104

Cited by 26 publications

(30 citation statements)

References 40 publications

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“…Replacement of the loop with the diglycine bridge did not result in any significant global disruptions of the structure of cdb3, as judged by pH-induced conformational changes, by binding to protein 4.1, and by binding of the N terminus to glycolytic enzymes. The role of this loop was later tested in an in vivo mouse model (32), where again results indicated a role for the ␤6-␤7 hairpin loop in ankyrin binding.…”

Section: Discussionmentioning

confidence: 99%

Determination of Structural Models of the Complex between the Cytoplasmic Domain of Erythrocyte Band 3 and Ankyrin-R Repeats 13–24

Kim

Brandon

Zhou

et al. 2011

Journal of Biological Chemistry

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The adaptor protein ankyrin-R interacts via its membrane binding domain with the cytoplasmic domain of the anion exchange protein (AE1) and via its spectrin binding domain with the spectrin-based membrane skeleton in human erythrocytes. This set of interactions provides a bridge between the lipid bilayer and the membrane skeleton, thereby stabilizing the membrane. Crystal structures for the dimeric cytoplasmic domain of AE1 (cdb3) and for a 12-ankyrin repeat segment (repeats 13-24) from the membrane binding domain of ankyrin-R (AnkD34) have been reported. However, structural data on how these proteins assemble to form a stable complex have not been reported. In the current studies, site-directed spin labeling, in combination with electron paramagnetic resonance (EPR) and double electron-electron resonance, has been utilized to map the binding interfaces of the two proteins in the complex and to obtain inter-protein distance constraints. These data have been utilized to construct a family of structural models that are consistent with the full range of experimental data. These models indicate that an extensive area on the peripheral domain of cdb3 binds to ankyrin repeats 18 -20 on the top loop surface of AnkD34 primarily through hydrophobic interactions. This is a previously uncharacterized surface for binding of cdb3 to AnkD34. Because a second dimer of cdb3 is known to bind to ankyrin repeats 7-12 of the membrane binding domain of ankyrin-R, the current models have significant implications regarding the structural nature of a tetrameric form of AE1 that is hypothesized to be involved in binding to full-length ankyrin-R in the erythrocyte membrane.Human erythrocytes exhibit an unusual biconcave disc shape and remarkable plasma membrane mechanical stability and deformability, all of which are necessary for their survival in the circulatory system. It is now well established that the unusual cell shape and membrane mechanical properties are due in large part to the presence of an extensive membrane skeleton, composed primarily of the proteins spectrin and actin, that lines the inner membrane surface and to specific bridging interactions between this membrane skeleton and intrinsic membrane proteins in the lipid bilayer. The spectrin-actin skeleton associates with the membrane bilayer via two types of contacts, one involving short actin protofilaments and protein 4.1, which interact with the cytoplasmic domain of glycophorin C, and the second involving the bridging protein ankyrin-R and protein 4.2, which interact with the cytoplasmic domain of the anion exchange protein (AE1) 3 also known as band 3. Alterations in this second class of interactions often result in spherical erythrocytes with decreased cell size and increased fragility, a condition known clinically as hereditary spherocytosis. Hereditary spherocytosis is a spectrum of inherited diseases, occurring in one family out of 2,000 -3,000, which present clinically as varying degrees of hemolytic anemia resulting from hemolysis of the spherical erythrocytes ...

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Section: Discussionmentioning

confidence: 99%

Determination of Structural Models of the Complex between the Cytoplasmic Domain of Erythrocyte Band 3 and Ankyrin-R Repeats 13–24

Kim

Brandon

Zhou

et al. 2011

Journal of Biological Chemistry

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“…The extreme N-terminal sequence of human AE1 binds multiple glycolytic enzymes (Campanella et al, 2008;Chu and Low, 2006) and hemoglobin under the control of hemoglobin oxygenation. Other parts of the N-terminal cytoplasmic domain provide binding sites for the erythroid cytoskeletal proteins ankyrin-1 (Chang and Low, 2003;Stefanovic et al, 2007), protein 4.2 (Toye et al, 2005), the ERM protein 4.1R (Salomao et al, 2008), and integrin-linked kinase (Keskanokwong et al, 2007). Solution of a 2.6 Å X-ray structure of the dimeric human erythroid AE1 cytoplasmic domain (amino acids 1-379) required crystallization at pH 4.8 and resolved residues 55-201 and 212-356 within a globular domain (Zhang et al, 2000).…”

Section: The Ae Anion Exchangers Among the Anion Transporters Of The mentioning

confidence: 99%

Molecular physiology and genetics of Na+-independent SLC4 anion exchangers

Alper

2009

Journal of Experimental Biology

194

220

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SUMMARY Plasmalemmal Cl–/HCO3–exchangers are encoded by the SLC4 and SLC26 gene superfamilies, and function to regulate intracellular pH,[Cl–] and cell volume. The Cl–/HCO3– exchangers of polarized epithelial cells also contribute to transepithelial secretion and reabsorption of acid–base equivalents and Cl–. This review focuses on Na+-independent electroneutral Cl–/HCO3– exchangers of the SLC4 family. Human SLC4A1/AE1 mutations cause the familial erythroid disorders of spherocytic anemia, stomatocytic anemia and ovalocytosis. A largely discrete set of AE1 mutations causes familial distal renal tubular acidosis. The Slc4a2/Ae2–/– mouse dies before weaning with achlorhydria and osteopetrosis. A hypomorphic Ae2–/– mouse survives to exhibit male infertility with defective spermatogenesis and a syndrome resembling primary biliary cirrhosis. A human SLC4A3/AE3 polymorphism is associated with seizure disorder, and the Ae3–/– mouse has increased seizure susceptibility. The transport mechanism of mammalian SLC4/AE polypeptides is that of electroneutral Cl–/anion exchange,but trout erythroid Ae1 also mediates Cl– conductance. Erythroid Ae1 may mediate the DIDS-sensitive Cl– conductance of mammalian erythrocytes, and, with a single missense mutation, can mediate electrogenic SO42–/Cl– exchange. AE1 trafficking in polarized cells is regulated by phosphorylation and by interaction with other proteins. AE2 exhibits isoform-specific patterns of acute inhibition by acidic intracellular pH and independently by acidic extracellular pH. In contrast, AE2 is activated by hypertonicity and, in a pH-independent manner, by ammonium and by hypertonicity. A growing body of structure–function and interaction data, together with emerging information about physiological function and structure, is advancing our understanding of SLC4 anion exchangers.

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“…Multiple binding sites for other proteins including cytoskeletal proteins ankyrin-1 (ANK1), glycolytic enzymes, and hemoglobin have been identified in the N-terminal domain of eAE1. [7][8][9][10][11] However, none of these appears to interact with the N terminus of kAE1. 9,12,13 The crystal structure of the N-terminal domain of eAE1 has been solved.…”

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confidence: 99%

Physical and Functional Links between Anion Exchanger-1 and Sodium Pump

Ya¹,

Al‐Lamki²,

Blake-Palmer³

et al. 2015

Journal of the American Society of Nephrology

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Anion exchanger-1 (AE1) mediates chloride-bicarbonate exchange across the plasma membranes of erythrocytes and, via a slightly shorter transcript, kidney epithelial cells. On an omnivorous human diet, kidney AE1 is mainly active basolaterally in a-intercalated cells of the collecting duct, where it is functionally coupled with apical proton pumps to maintain normal acid-base homeostasis. The C-terminal tail of AE1 has an important role in its polarized membrane residency. We have identified the b1 subunit of Na + , K + -ATPase (sodium pump) as a binding partner for AE1 in the human kidney. Kidney AE1 and b1 colocalized in renal a-intercalated cells and coimmunoprecipitated (together with the catalytic a1 subunit of the sodium pump) from human kidney membrane fractions. ELISA and fluorescence titration assays confirmed that AE1 and b1 interact directly, with a K d value of 0.81 mM. GST-AE1 pull-down assays using human kidney membrane proteins showed that the last 11 residues of AE1 are important for b1 binding. siRNAinduced knockdown of b1 in cell culture resulted in a significant reduction in kidney AE1 levels at the cell membrane, whereas overexpression of kidney AE1 increased cell surface sodium pump levels. Notably, membrane staining of b1 was reduced throughout collecting ducts of AE1-null mouse kidney, where increased fractional excretion of sodium has been reported. These data suggest a requirement of b1 for proper kidney AE1 membrane residency, and that activities of AE1 and the sodium pump are coregulated in kidney.

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An 11-amino acid β-hairpin loop in the cytoplasmic domain of band 3 is responsible for ankyrin binding in mouse erythrocytes

Cited by 26 publications

References 40 publications

Determination of Structural Models of the Complex between the Cytoplasmic Domain of Erythrocyte Band 3 and Ankyrin-R Repeats 13–24

Determination of Structural Models of the Complex between the Cytoplasmic Domain of Erythrocyte Band 3 and Ankyrin-R Repeats 13–24

Molecular physiology and genetics of Na+-independent SLC4 anion exchangers

Physical and Functional Links between Anion Exchanger-1 and Sodium Pump

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