Interaction between red cell membrane band 3 and cytosolic carbonic anhydrase

Kifor, Gabriela; Toon, Michael R.; Jànoshàzi, Àgnes; Solomon, A. K.

doi:10.1007/bf00234498

Cited by 48 publications

(31 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…CAII provides the substrate for bicarbonate efflux by AE1 and converts the bicarbonate that enters via AE1 to CO 2 and H 2 O. Early studies suggest that AE1 and CAII form a complex (31). The CAII binding site on AE1 was recently identified as the acidic motif LDADD in the carboxyl-terminal tail of AE1 (30,32).…”

Section: Resultsmentioning

confidence: 99%

“…This interaction is weak, however, because the bulk of carbonic anhydrase can be readily removed from isolated erythrocyte membranes (29,30). Reaction of an anion transport inhibitor (DIDS) with AE1 altered the binding of a fluorescent inhibitor to carbonic anhydrase, suggesting a physical link between these two proteins (31). Extracellular lectin caused agglutination of AE1 and a similar redistribution of CAII on the cytosolic surface of the erythrocyte membrane (30), suggesting a physical interaction of AE1 with CAII.…”

mentioning

confidence: 99%

See 1 more Smart Citation

A Transport Metabolon

Sterling

Reithmeier

Casey

2001

Journal of Biological Chemistry

334

153

View full text Add to dashboard Cite

The cytoplasmic carboxyl-terminal domain of AE1, the plasma membrane chloride/bicarbonate exchanger of erythrocytes, contains a binding site for carbonic anhydrase II (CAII). To examine the physiological role of the AE1/CAII interaction, anion exchange activity of transfected HEK293 cells was monitored by following the changes in intracellular pH associated with AE1-mediated bicarbonate transport. AE1-mediated chloride/bicarbonate exchange was reduced 50 -60% by inhibition of endogenous carbonic anhydrase with acetazolamide, which indicates that CAII activity is required for full anion transport activity. AE1 mutants, unable to bind CAII, had significantly lower transport activity than wild-type AE1 (10% of wild-type activity), suggesting that a direct interaction was required. To determine the effect of displacement of endogenous wild-type CAII from its binding site on AE1, AE1-transfected HEK293 cells were co-transfected with cDNA for a functionally inactive CAII mutant, V143Y. AE1 activity was maximally inhibited 61 ؎ 4% in the presence of V143Y CAII. A similar effect of V143Y CAII was found for AE2 and AE3cardiac anion exchanger isoforms. We conclude that the binding of CAII to the AE1 carboxyl-terminus potentiates anion transport activity and allows for maximal transport. The interaction of CAII with AE1 forms a transport metabolon, a membrane protein complex involved in regulation of bicarbonate metabolism and transport.Carbon dioxide, the metabolic end product of oxidative respiration, must be effectively cleared from the human body. CO 2 diffuses out of cells into the blood stream and into erythrocytes, where it is hydrated by cytosolic carbonic anhydrase (CA). 1 The resulting membrane-impermeant HCO 3 Ϫ is exported into the plasma by the plasma membrane Cl Ϫ /HCO 3 Ϫ anion exchanger (AE1), thus increasing the blood capacity for carrying CO 2 . Upon returning to the lungs the process is reversed; HCO 3 Ϫ is transported into the erythrocyte in exchange for Cl Ϫ by AE1 and dehydrated by CA, and the resulting CO 2 diffuses across the erythrocyte and alveolar membranes to be expired from the body. The 5 ϫ 10 4 s Ϫ1 turnover rate of AE1 (1) and the high content of AE1 in the membrane (2) facilitate completion of bicarbonate transport within 50 ms during passage of an erythrocyte through a capillary (3).AE1 is a 911-amino acid polytopic glycoprotein that facilitates the one for one electroneutral exchange of Cl Ϫ for HCO 3

show abstract

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

A Transport Metabolon

Sterling

Reithmeier

Casey

2001

Journal of Biological Chemistry

334

153

View full text Add to dashboard Cite

show abstract

“…A transport metabolon is a physical complex of an enzyme and a transporter, which maximizes and may regulate substrate flux through the enzyme and across the membrane. The first example of a bicarbonate transport metabolon was provided by anion exchangers of the AE family, which form a functional and physical complex with cytosolic CAII (18,25,45) and with the extracellular enzyme, CAIV (40). NBC1 and NBC3 also form a metabolon with CAII [B. Alvarez, F. Loiselle, and J. Casey, unpublished observation (NBC1) and F. Loiselle and J. Casey, unpublished observation (NBC3)].…”

Section: Discussionmentioning

confidence: 99%

The functional and physical relationship between the DRA bicarbonate transporter and carbonic anhydrase II

Sterling

Brown

Supuran

et al. 2002

American Journal of Physiology-Cell Physiology

View full text Add to dashboard Cite

terminal cytoplasmic tails of chloride/bicarbonate anion exchangers (AE) bind cytosolic carbonic anhydrase II (CAII) to form a bicarbonate transport metabolon, a membrane protein complex that accelerates transmembrane bicarbonate flux. To determine whether interaction with CAII affects the downregulated in adenoma (DRA) chloride/bicarbonate exchanger, anion exchange activity of DRA-transfected HEK-293 cells was monitored by following changes in intracellular pH associated with bicarbonate transport. DRA-mediated bicarbonate transport activity of 18 Ϯ 1 mM H ϩ equivalents/min was inhibited 53 Ϯ 2% by 100 mM of the CAII inhibitor, acetazolamide, but was unaffected by the membrane-impermeant carbonic anhydrase inhibitor, 1-[5-sulfamoyl-1,3,4-thiadiazol-2-yl-(aminosulfonyl-4-phenyl)]-2,6-dimethyl-4-phenyl-pyridinium perchlorate. Compared with AE1, the COOH-terminal tail of DRA interacted weakly with CAII. Overexpression of a functionally inactive CAII mutant, V143Y, reduced AE1 transport activity by 61 Ϯ 4% without effect on DRA transport activity (105 Ϯ 7% transport activity relative to DRA alone). We conclude that cytosolic CAII is required for full DRA-mediated bicarbonate transport. However, DRA differs from other bicarbonate transport proteins because its transport activity is not stimulated by direct interaction with CAII. metabolon; chloride/bicarbonate exchanger; downregulated in adenoma BICARBONATE METABOLISM is essential in humans, because carbon dioxide is the metabolic end product of respiratory oxidation and CO 2 /HCO 3 Ϫ is the body's primary pH buffer system. The bicarbonate transport superfamily of genes (SLC4 and SLC26 gene families), responsible for transmembrane movement of membrane-impermeant HCO 3 Ϫ , comprises the Cl Ϫ /HCO 3 Ϫ anion exchanger (AE) family (1,19,20), the Na ϩ /HCO 3 Ϫ cotransporter proteins (NBC) (3, 4), and the recently identified proteins pendrin (9, 32, 37) and downregulated in adenoma (DRA) (23, 27, 48).Several lines of evidence have demonstrated an interaction between cytosolic carbonic anhydrase II (CAII) and the AE1, AE2, and AE3 anion exchanger isoforms. Binding of erythrocyte membranes to CAII increased CAII enzymatic activity (25), which suggests an interaction between these two proteins. CAII can be coimmunoprecipitated with solubilized AE1 and incubation with an extracellular lectin-caused agglutination of AE1 and a similar redistribution of CAII on the cytosolic surface of the erythrocyte membrane (45). A sensitive microtiter binding assay, using truncation and point mutation of the AE1 COOH terminus, led to the identification of the binding site of CAII in AE1 as LDADD (amino acids 886-890) (46) and the basic amino-terminal region of CAII as the binding site for AE1 (44).The functional consequences of the AE/CAII interaction have been studied (42). Using HEK-293 cells transiently transfected with AE1 cDNA, we determined that inhibition of endogenous CAII activity with acetazolamide resulted in a decrease of AE1 transport activity. Mutation of the AE1, LDADD, and CA...

show abstract

“…Cytosolic CAII has been found to bind to and facilitate transport function of many acid/base transporting membrane proteins, including the Cl Ϫ /HCO 3 Ϫ exchangers AE1 and AE2 (25)(26)(27)(28)(29), the Na ϩ /HCO 3 Ϫ cotransporters NBCe1 and NBCn1 (30 -36) and the Na ϩ /H ϩ exchanger NHE1 (37,38), a phenomenon coined "transport metabolon." In all cases, CAII was found to bind to an acidic cluster within the C-terminal tail of the transport protein.…”

mentioning

confidence: 99%

Analysis of the Binding Moiety Mediating the Interaction between Monocarboxylate Transporters and Carbonic Anhydrase II

Noor¹,

Dietz²,

Heidtmann

et al. 2015

Journal of Biological Chemistry

View full text Add to dashboard Cite

Background: Carbonic anhydrase II (CAII) augments activity of monocarboxylate transporters (MCTs) by noncatalytic interaction. Results: CAII binds to an acidic cluster with an appropriate context in the MCT C terminus. Conclusion: Isoform-specific interaction between MCTs and CAII requires a specific binding moiety. Significance: CAII-mediated increase in lactate transport depends on the presence of a specific binding moiety in MCT.Proton-coupled monocarboxylate transporters (MCTs) mediate the exchange of high energy metabolites like lactate between different cells and tissues. We have reported previously that carbonic anhydrase II augments transport activity of MCT1 and MCT4 by a noncatalytic mechanism, while leaving transport activity of MCT2 unaltered. In the present study, we combined electrophysiological measurements in Xenopus oocytes and pulldown experiments to analyze the direct interaction between carbonic anhydrase II (CAII) and MCT1, MCT2, and MCT4, respectively. Transport activity of MCT2-WT, which lacks a putative CAII-binding site, is not augmented by CAII. However, introduction of a CAII-binding site into the C terminus of MCT2 resulted in CAII-mediated facilitation of MCT2 transport activity. Interestingly, introduction of three glutamic acid residues alone was not sufficient to establish a direct interaction between MCT2 and CAII, but the cluster had to be arranged in a fashion that allowed access to the binding moiety in CAII. We further demonstrate that functional interaction between MCT4 and CAII requires direct binding of the enzyme to the acidic cluster 431 EEE in the C terminus of MCT4 in a similar fashion as previously shown for binding of CAII to the cluster 489 EEE in the C terminus of MCT1. In CAII, binding to MCT1 and MCT4 is mediated by a histidine residue at position 64. Taken together, our results suggest that facilitation of MCT transport activity by CAII requires direct binding between histidine 64 in CAII and a cluster of glutamic acid residues in the C terminus of the transporter that has to be positioned in surroundings that allow access to CAII.

show abstract

Interaction between red cell membrane band 3 and cytosolic carbonic anhydrase

Cited by 48 publications

References 28 publications

A Transport Metabolon

A Transport Metabolon

The functional and physical relationship between the DRA bicarbonate transporter and carbonic anhydrase II

Analysis of the Binding Moiety Mediating the Interaction between Monocarboxylate Transporters and Carbonic Anhydrase II

Contact Info

Product

Resources

About