| Dataset | KEGG Pathways 2026 |
| Category | structural or functional annotations |
| Type | pathway |
| Description | One of the major tasks of the renal proximal tubule (PT) is to secrete acid into the tubule lumen, thereby reabsorbing approximately 80% of the filtered bicarbonate (HCO3(-)), as well as generating "new HCO3(-)" for regulating blood pH. In the tubular lumen, filtered HCO3(-) combines with H(+) in a reaction catalyzed by CA IV. The CO2 thus produced rapidly diffuses into the tubular cells and is combined with water to produce intracellular H(+) and HCO3(-), catalyzed by soluble cytoplasmic CA II. HCO3(-) is then cotransported with Na(+) into blood via the NBC-1. The intracellular H(+) produced by CA II is secreted into the tubular lumen predominantly via the NHE-3. The PT creates the "new HCO3(-)" by taking glutamine and metabolizing it to two molecules each of NH4(+) and HCO3(-). The NH4(+) is excreted into the tubular lumen, and the HCO3(-) , which is "new HCO3(-) ," is returned to the blood, where it replaces the HCO3(-) lost earlier in the titration of nonvolatile acids. (Kyoto Encyclopedia of Genes and Genomes, hsa04964) |
| External Link | https://www.kegg.jp/entry/hsa04964 |
| Similar Terms | |
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21 proteins participating in the Proximal tubule bicarbonate reclamation pathway from the KEGG Pathways 2026 dataset.
| Symbol | Name |
|---|---|
| ATP1A2 | ATPase, Na+/K+ transporting, alpha 2 polypeptide |
| ATP1A3 | ATPase, Na+/K+ transporting, alpha 3 polypeptide |
| ATP1A4 | ATPase, Na+/K+ transporting, alpha 4 polypeptide |
| ATP1B1 | ATPase, Na+/K+ transporting, beta 1 polypeptide |
| ATP1B2 | ATPase, Na+/K+ transporting, beta 2 polypeptide |
| ATP1B3 | ATPase, Na+/K+ transporting, beta 3 polypeptide |
| ATP1B4 | ATPase, Na+/K+ transporting, beta 4 polypeptide |
| CA2 | carbonic anhydrase II |
| CA4 | carbonic anhydrase IV |
| FXYD2 | FXYD domain containing ion transport regulator 2 |
| GLS2 | glutaminase 2 (liver, mitochondrial) |
| GRID1 | glutamate receptor, ionotropic, delta 1 |
| GRID2 | glutamate receptor, ionotropic, delta 2 |
| MDH1 | malate dehydrogenase 1, NAD (soluble) |
| MINDY4 | MINDY lysine 48 deubiquitinase 4 |
| PCK1 | phosphoenolpyruvate carboxykinase 1 (soluble) |
| PCK2 | phosphoenolpyruvate carboxykinase 2 (mitochondrial) |
| SLC25A10 | solute carrier family 25 (mitochondrial carrier; dicarboxylate transporter), member 10 |
| SLC38A3 | solute carrier family 38, member 3 |
| SLC4A4 | solute carrier family 4 (sodium bicarbonate cotransporter), member 4 |
| SLC9A3 | solute carrier family 9, subfamily A (NHE3, cation proton antiporter 3), member 3 |
