Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have recently cloned and characterized a unique sodium bicarbonate cotransporter, NBC3, which unlike other members of the NBC family, is ethylisopropylamiloride (EIPA) inhibitable, DIDS insensitive, and electroneutral (A. Pushkin, N. Abuladze, I. Lee, D. Newman, J. Hwang, and I. Kurtz. J. Biol. Chem. 274: 16569-16575, 1999). In the present study, a specific polyclonal antipeptide COOH-terminal antibody, NBC3-C1, was generated and used to determine the pattern of NBC3 protein expression in rabbit kidney. A major band of approximately 200 kDa was detected on immunoblots of rabbit kidney. Immunocytochemistry of rabbit kidney frozen sections revealed specific staining of the apical membrane of intercalated cells in both the cortical and outer medullary collecting ducts. The pattern of NBC3 protein expression in the collecting duct was nearly identical to the same sections stained with an antibody against the vacuolar H+-ATPase 31-kDa subunit. In addition, the NBC3-C1 antibody coimmunoprecipitated the vacuolar H+-ATPase 31-kDa subunit. Functional studies in outer medullary collecting ducts (inner stripe) showed that type A intercalated cells have an apical Na+-dependent base transporter that is EIPA inhibitable and DIDS insensitive. The data suggest that NBC3 participates in H+/base transport in the collecting duct. The close association of NBC3 and the vacuolar H+-ATPase in type A intercalated cells suggests a potential structural/functional interaction between the two transporters.
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PMID:NBC3 expression in rabbit collecting duct: colocalization with vacuolar H+-ATPase. 1060 Sep 45

In the present study, we produced a rabbit peptide-derived polyclonal COOH-terminal antibody that selectively recognizes NBC3, to determine the cellular and subcellular localization of NBC3 in rat kidney, using immunocytochemistry and immunoelectron microscopy. Immunocytochemistry with cryostat sections and semithin cryosections revealed specific staining of intercalated cells (ICs) in the connecting tubule and in cortical, outer medullary, and initial inner medullary collecting ducts. In the connecting tubule and in the cortical and medullary collecting duct, the labeling was associated with both type A and type B ICs. In type A ICs, labeling was confined to the apical and subapical domains, whereas in type B ICs, basal domains were exclusively labeled. In contrast, collecting duct principal cells were consistently unlabeled, and this was confirmed using anti-aquaporin-2 antibodies, which labeled principal cells in parallel semithin cryosections. Glomeruli, proximal tubules, descending thin limbs, ascending thin limbs, thick ascending limbs, distal convoluted tubules, and vascular structures were unlabeled. For immunoelectron microscopy, tissue samples were freeze-substituted, and immunolabeling was performed on ultrathin Lowicryl HM20 sections. Immunoelectron microscopy demonstrated that NBC3 labeling was very abundant in the apical plasma membrane, in intracellular vesicles, and in tubulocisternal profiles in the subapical domains of type A ICs. In type B ICs, NBC3 was mainly present in the basolateral plasma membrane. Immunolabeling controls using peptide-absorbed antibody were consistently negative. In conclusion, NBC3 is highly abundant in the apical plasma membrane of type A ICs and in the basolateral plasma membrane of type B ICs. This suggests that NBC3 plays an important role in modulating bicarbonate transport in the connecting tubule and collecting duct.
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PMID:Immunoelectron microscopic localization of NBC3 sodium-bicarbonate cotransporter in rat kidney. 1066 37

In the male reproductive tract, the epididymis plays an important role in mediating transepithelial bicarbonate transport and luminal acidification. In the proximal vas deferens, a significant component of luminal acidification is Na+-independent, and mediated by specific cells that possess apical vacuolar proton pumps. In contrast, luminal acidification in the cauda epididymidis is an Na+-dependent process. The specific apical Na+-dependent H+/base transport process(es) responsible for luminal acidification have not been identified. A potential clue as to the identity of these apical Na+-dependent H+/base transporter(s) is provided by similarities between the transport properties of the epididymis and the mammalian nephron. Specifically, the H+/base transport properties of caput epididymidis resemble the mammalian renal proximal tubule, whereas the distal epididymis and vas deferens have characteristics in common with renal collecting duct intercalated cells. Given the known expression of the Na+/H+ antiporter, NHE3, in the proximal tubule, and of the electroneutral sodium bicarbonate cotransporter, NBC3, in renal intercalated cells, we determined the localization of NHE3 and NBC3 in various regions of rat epididymis. NBC3 was highly expressed on the apical membrane of apical (narrow) cells in caput epididymidis, and light (clear) cells in corpus and cauda epididymidis. The number of cells expressing apical NBC3 was highest in cauda epididymidis. The localization of NBC3 in the epididymis was identical to the vacuolar H+-ATPase. The results indicate that colocalization of NBC3 and the vacuolar H+-ATPase is not restricted to kidney intercalated cells. Moreover, the close association of the two transporters appears to be a more generalized phenomenon in cells that express high levels of vacuolar H+-ATPase. Unlike NBC3, NHE3 was most highly expressed on the apical membrane of all epithelial cells in caput epididymidis, with less expression in the corpus, and no expression in the cauda. These results suggest that apical NBC3 and NHE3 potentially play an important role in mediating luminal H+/base transport in epididymis.
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PMID:Immunolocalization of NBC3 and NHE3 in the rat epididymis: colocalization of NBC3 and the vacuolar H+-ATPase. 1097 18

The outer medullary collecting duct (OMCD) plays an important role in mediating transepithelial HCO transport [J(HCO(3)(-))] and urinary acidification. HCO absorption by type A intercalated cells in the OMCD inner stripe (OMCD(is)) segment is thought to by mediated by an apical vacuolar H(+)-ATPase and H(+)-K(+)-ATPase coupled to a basolateral Cl(-)-HCO exchanger (AE1). Besides these Na(+)-independent transporters, previous studies have shown that OMCD(is) type A intercalated cells have an apical electroneutral EIPA-sensitive, DIDS-insensitive Na(+)-HCO cotransporter (NBC3); a basolateral Na(+)/H(+) antiporter; and a basolateral Na(+)-K(+)-ATPase. In this study, we reexamined the Na(+) dependence of transepithelial Na(+) transport in the OMCD(is) and determined the role of apical NBC3 in intracellular (pH(i)) regulation in OMCD(is) type A intercalated cells. Control tubules absorbed HCO at a rate of approximately 13 pmol. min(-1). mm(-1). Lowering luminal Na(+) from 140 to 40 mM decreased [J(HCO(3)(-))] by approximately 15% without a change in transepithelial potential (V(te)). Furthermore, 50 microM EIPA (lumen) also decreased [J(HCO(3)(-))] by approximately 13% without a change in V(te). The effect of lowering luminal Na(+) and adding EIPA were not additive. These results demonstrate that [J(HCO(3)(-))] in the OMCD(is) is in part Na(+) dependent. In separate experiments, the pH(i) recovery rate after an NH prepulse was monitored in single type A intercalated cells with confocal fluorescence microscopy. The pH(i) recovery rate was approximately 0.21 pH/min in Na(+)-containing solutions and decreased to approximately 0.16 pH/min with EIPA (50 microM, lumen). In tubules perfused/bathed without Na(+), luminal Na(+) addition resulted in a pH(i) recovery rate of approximately 0.36 pH/min, whereas the Na(+)-independent recovery rate was approximately 0.16 pH/min. EIPA (50 microM, lumen) decreased the Na(+)-dependent pH(i) recovery rate to approximately 0.07 pH/min. The Na(+)-independent recovery rate was decreased to approximately 0.06 pH/min by bafilomycin (10 nM, lumen) and to approximately 0.10 pH/min using Schering 28080 (10 microM, lumen). These findings indicate that NBC3 contributes to pH(i) regulation in OMCD(is) type A intercalated cells and plays only a minor role in mediating [J(HCO(3)(-))] in the OMCD(is).
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PMID:Apical H(+)/base transporters mediating bicarbonate absorption and pH(i) regulation in the OMCD. 1237 86

Large-scale phosphoproteomic analysis employing liquid chromatography-tandem mass spectrometry (LC-MS/MS) often requires a significant amount of manual manipulation of phosphopeptide datasets in the post-acquisition phase. To assist in this process, we have created software, PhosphoPIC (PhosphoPeptide Identification and Compilation), which can perform a variety of useful functions including automated selection and compilation of phosphopeptide identifications from multiple MS levels, estimation of dataset false discovery rate, and application of appropriate cross-correlation (XCorr) filters. In addition, the output files generated by this program are compatible with downstream phosphorylation site assignment using the Ascore algorithm, as well as phosphopeptide quantification via QUOIL. In this report, we utilized this software to analyze phosphoproteins from short-term vasopressin-treated rat kidney inner medullary collecting duct (IMCD). A total of 925 phosphopeptides representing 173 unique proteins were identified from membrane-enriched fractions of IMCD with a false discovery rate of 1.5%. Of these proteins, 106 were found only in the membrane-enriched fraction of IMCD cells and not in whole IMCD cell lysates. These identifications included a number of well-studied ion and solute transporters including ClC-1, LAT4, MCT2, NBC3, and NHE1, all of which contained novel phosphorylation sites. Using a label-free quantification approach, we identified phosphoproteins that changed in abundance with vasopressin exposure including aquaporin-2 (AQP2), Hnrpa3, IP3 receptor 3, and pur-beta.
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PMID:An automated platform for analysis of phosphoproteomic datasets: application to kidney collecting duct phosphoproteins. 1768 30