Enzymes
| UniProtKB help_outline | 296 proteins |
Reaction participants Show >> << Hide
- Name help_outline K+ Identifier CHEBI:29103 (CAS: 24203-36-9) help_outline Charge 1 Formula K InChIKeyhelp_outline NPYPAHLBTDXSSS-UHFFFAOYSA-N SMILEShelp_outline [K+] 2D coordinates Mol file for the small molecule Search links Involved in 17 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline hydrogencarbonate Identifier CHEBI:17544 (Beilstein: 3903504; CAS: 71-52-3) help_outline Charge -1 Formula CHO3 InChIKeyhelp_outline BVKZGUZCCUSVTD-UHFFFAOYSA-M SMILEShelp_outline OC([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 59 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline chloride Identifier CHEBI:17996 (Beilstein: 3587171; CAS: 16887-00-6) help_outline Charge -1 Formula Cl InChIKeyhelp_outline VEXZGXHMUGYJMC-UHFFFAOYSA-M SMILEShelp_outline [Cl-] 2D coordinates Mol file for the small molecule Search links Involved in 143 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:75059 | RHEA:75060 | RHEA:75061 | RHEA:75062 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
| UniProtKB help_outline |
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Publications
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Ae4 (Slc4a9) is an electroneutral monovalent cation-dependent Cl-/HCO3- exchanger.
Pena-Muenzenmayer G., George A.T., Shull G.E., Melvin J.E., Catalan M.A.
Ae4 (Slc4a9) belongs to the Slc4a family of Cl(-)/HCO3 (-) exchangers and Na(+)-HCO3 (-) cotransporters, but its ion transport cycle is poorly understood. In this study, we find that native Ae4 activity in mouse salivary gland acinar cells supports Na(+)-dependent Cl(-)/HCO3 (-) exchange that is c ... >> More
Ae4 (Slc4a9) belongs to the Slc4a family of Cl(-)/HCO3 (-) exchangers and Na(+)-HCO3 (-) cotransporters, but its ion transport cycle is poorly understood. In this study, we find that native Ae4 activity in mouse salivary gland acinar cells supports Na(+)-dependent Cl(-)/HCO3 (-) exchange that is comparable with that obtained upon heterologous expression of mouse Ae4 and human AE4 in CHO-K1 cells. Additionally, whole cell recordings and ion concentration measurements demonstrate that Na(+) is transported by Ae4 in the same direction as HCO3 (-) (and opposite to that of Cl(-)) and that ion transport is not associated with changes in membrane potential. We also find that Ae4 can mediate Na(+)-HCO3 (-) cotransport-like activity under Cl(-)-free conditions. However, whole cell recordings show that this apparent Na(+)-HCO3 (-) cotransport activity is in fact electroneutral HCO3 (-)/Na(+)-HCO3 (-) exchange. Although the Ae4 anion exchanger is thought to regulate intracellular Cl(-) concentration in exocrine gland acinar cells, our thermodynamic calculations predict that the intracellular Na(+), Cl(-), and HCO3 (-) concentrations required for Ae4-mediated Cl(-) influx differ markedly from those reported for acinar secretory cells at rest or under sustained stimulation. Given that K(+) ions share many properties with Na(+) ions and reach intracellular concentrations of 140-150 mM (essentially the same as extracellular [Na(+)]), we hypothesize that Ae4 could mediate K(+)-dependent Cl(-)/HCO3 (-) exchange. Indeed, we find that Ae4 mediates Cl(-)/HCO3 (-) exchange activity in the presence of K(+) as well as Cs(+), Li(+), and Rb(+) In summary, our results strongly suggest that Ae4 is an electroneutral Cl(-)/nonselective cation-HCO3 (-) exchanger. We postulate that the physiological role of Ae4 in secretory cells is to promote Cl(-) influx in exchange for K(+)(Na(+)) and HCO3 (-) ions. << Less
J. Gen. Physiol. 147:423-436(2016) [PubMed] [EuropePMC]
This publication is cited by 4 other entries.