UNIPROT:P41181 - FACTA Search

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Query: UNIPROT:P41181 (collecting duct)
5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intercalated cells (ICs) in the collecting duct and the connecting tubule (CNT) are involved in H+ secretion and HCO3- reabsorption. H+ secretion is mediated by an H(+)-adenosinetriphosphatase in the apical plasma membrane, whereas a band 3-like Cl(-)-HCO3- exchanger in the basolateral membrane is responsible for HCO3- reabsorption. Recent studies have reported that a band 3-like protein is also present in mitochondria in rabbit ICs. The purpose of this study was to establish the subcellular location of the band 3-like Cl(-)-HCO3- exchanger in rabbit ICs by electron microscopic immunocytochemistry using a monoclonal antibody, IVF12, against erythrocyte band 3 protein. Rabbit kidneys were preserved by in vivo perfusion with a paraformaldehyde-lysine-periodate solution and processed for immunocytochemistry using a horseradish peroxidase preembedding technique. Band 3 immunostaining was observed on the basolateral plasma membrane of ICs in the outer medullary collecting duct and type A cells in the cortical collecting duct (CCD) and CNT. In addition, distinct staining for band 3 was present in numerous small vesicles and in multivesicular bodies in type A ICs in the CCD and CNT. However, there was no evidence of band 3 immunostaining of mitochondria or of the apical plasma membrane in any cells of the collecting duct. These observations suggest that basolateral Cl(-)-HCO3- exchangers in type A ICs in the rabbit kidney are stored in intracellular vesicles and possibly degraded in the vascular-lysosomal system when these cells are in a resting state. The previously reported band 3 immunolabeling of mitochondria could not be confirmed.
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PMID:Intracellular band 3 immunostaining in type A intercalated cells of rabbit kidney. 137 72

Two major types of intercalated cells (IC) have been previously defined in rabbit collecting duct: alpha-cells have a basolateral band 3-like anion exchanger and secrete H+, whereas beta-cells bind peanut agglutinin (PNA) apically and are believed to secrete HCO3-. To further define IC types, we double-labeled kidney sections with anti-H(+) -ATPase antibodies and with either an anti-band 3 antibody or PNA. We found four patterns of staining: 1) IC with apical H(+)-ATPase and basal band 3, a configuration consistent with ongoing H+ secretion, which prevailed in the inner stripe of outer medulla (OMCDi); 2) diffuse H(+)-ATPase labeling across the cell and basal band 3, which was most numerous in the outer stripe of outer medulla (OMCDo); 3) IC with "bright" apical peanut lectin, diffuse H(+)-ATPase, and no band 3, which was abundant in the cortical collecting duct (CCD) and probably represents HCO3(-)-secreting cells; and 4) "hybrid" cells with various staining combinations (e.g., apical lectin binding and apical H(+)-ATPase), which although they are uncommon, were seen in the CCD. Consistent with this immunocytochemical finding of hybrid cells, cell-sorting studies on isolated CCD IC showed that 6-18% of PNA-positive cells also stained positively for band 3. We conclude that 1) band 3-positive IC in the OMCD vary axially. Most OMCDi IC are probably active proton secretors, whereas up to one-half of OMCDo IC may be latent H+ secretors. 2) The diffuse H(+)-ATPase pattern in putative beta-cells differs from comparable results in the rat and is not consistent with a "reversed" alpha-cell. HCO3- secretion by beta-cells may be driven by an H+ extrusion mechanism other than the alpha-cell pump re-sorted to the basolateral membrane. 3) The possibility of hybrid cells that might combine alpha- and beta-cell transport proteins suggests a mechanism for functional reversal of collecting duct IC polarity.
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PMID:Colocalization of H(+)-ATPase and band 3 anion exchanger in rabbit collecting duct intercalated cells. 184 62

The turtle urinary bladder serves as a model for collecting duct functions in the mammalian kidney. The epithelium of both the turtle bladder and the mammalian collecting duct can generate a steep gradient for H+ ions between blood and urine. Secretion of H+ into the urine is coupled to a basolateral efflux of HCO-3 that appears to be exchanged mainly against Cl-. Here we show that approximately 80% of the dark cells of the bladder contain a 110,000 relative molecular weight (Mr) analogue of the turtle erythrocyte anion exchanger, band 3. The band 3 analogue is confined to the basolateral cell surface and is absent from the apical membrane. A minor population of the dark cells (approximately 20%), which have been previously suggested to represent reverse cells that are involved in HCO-3 secretion rather than absorption, appears not to express a band 3-like anion exchanger, at either the apical or the basolateral membrane. The bladder band 3 protein is colocalized with actin and isoforms of ankyrin (200,000 Mr) and spectrin (230,000 Mr) along the basolateral membrane. Linkage of band 3 via ankyrin to the spectrin-actin lattice may restrict this anion exchanger to the basolateral membrane surface. In view of our previous observation of a band 3-like anion exchanger in the collecting duct epithelium of the rat kidney, these findings point to a common molecular basis for acid-base transport in the mammalian collecting duct and the reptilian urinary bladder.
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PMID:Band 3 is the basolateral anion exchanger of dark epithelial cells of turtle urinary bladder. 355 10

Poly- and monoclonal antibodies have been prepared against the cytoplasmic domain (43 kDa) and the 17-, 20-, and 35-kDa fragments of the membrane-spanning domain of the human erythrocyte anion exchanger, band 3. The antibodies were used to localize and further characterize analogues of band 3 in the human kidney. We report here that the basolateral membrane of intercalated cells of the connecting tubules and collecting ducts contains an analogue of band 3 that appears to be highly homologous to the erythrocyte anion exchanger. This band 3-like protein is probably important for reabsorption of bicarbonate in the collecting duct system and thus for acidification of the forming urine. The band 3-like protein of the intercalated cells contain immunoreactive sites of both the cytoplasmic domain and the three major fragments of the membrane-spanning domain of erythrocyte band 3. Although no immunological differences were detected between the membrane-spanning domains of band 3 in erythrocytes and intercalated cells, there are at least three sites along the cytoplasmic domain of kidney band 3 that differ from erythrocyte band 3 in either amino acid composition or posttranslational modifications. The main kidney analogue of band 3 that contains epitopes of the cytoplasmic domain as well as the 17- and 35-kDa membrane-spanning domain of erythroid band 3 is a polypeptide with an apparent molecular mass of 100-110 kDa. Further immunoreactive polypeptides at approximately 180, approximately 140, approximately 38, approximately 25-30 kDa that were detected at lower stringency and higher sensitivity of the immunoblotting procedure may be members of a multigene family that encodes a series of related proteins.
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PMID:Immunochemical characterization of a band 3-like anion exchanger in collecting duct of human kidney. 361 86

Previous studies have demonstrated the presence of two populations of Na,K-ATPase with distinct kinetic, pharmacological and immunological characteristics along the rabbit nephron, indicating that the proximal segments of the nephron express exclusively the alpha 1 isoform of the catalytic subunit, whereas the collecting duct expresses an alpha 3-like isoform. Because pharmacological studies have shown the existence of two populations of Na,K-ATPase with different sensitivities to ouabain in the rat cortical collecting duct, which may result from the presence in the same nephron segment of the two isoforms demonstrated in the different segments of the rabbit nephron, the present study was undertaken to characterize the properties of Na,K-ATPase along the rat nephron. Results indicate that each segment of the rat nephron contains two subpopulations of Na,K-ATPase: a component highly sensitive to ouabain (IC50 approximately 5.10(-6) M) which is recognized by an anti-alpha 3 antibody and another moiety of lower affinity for ouabain (IC50 approximately 5.10(-4) M) which is recognized by an anti-alpha 1 antibody. Whether these two subpopulations correspond to different isoforms of the alpha subunit of Na,K-ATPase (alpha 1 and alpha 3-like) remains to be determined.
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PMID:Presence of two isoforms of Na, K-ATPase with different pharmacological and immunological properties in the rat kidney. 767 30

The newborn is limited in its ability to respond to acid-base perturbations. To investigate the development of renal H+/HCO3- transport mechanisms, we probed acid-base-related epitopes in the mesonephric and developing metanephric kidneys of rabbits. Using immunofluorescence with monoclonal antibodies to the vacuolar H+ATPase, band 3-like Cl-/HCO3- exchanger, and apical surface of fully differentiated beta-intercalated cells, and peanut lectin cytochemistry (another marker of beta-intercalated cells), we found that these epitopes were poorly expressed in the nephrogenic zone of the newborn kidney cortex. Deeper in the cortex, collecting ducts showed weak apical staining with beta-intercalated cell antibodies and two patterns of staining with the H+ATPase and band 3 antibodies: polar and circumferential or diffuse. Some cells showed apical staining with H+ATPase while others showed diffuse staining, similar to that observed in the mature cortical collecting duct. Band 3 labeling was basolateral, as observed in the adult, and diffuse, which was rarely seen in mature kidney sections. Newborn outer medullary collecting ducts showed apical labeling with H+ATPase and basolateral staining with band 3 antibodies, similar to the mature outer medulla. Surprisingly, the mesonephric collecting tubule showed cells with apical H+ATPase staining or basolateral band 3 labeling and, less frequently, cells with positive staining for beta-intercalated cells. The relative maturity of the mesonephric collecting tubule and similarity to what is observed in mature metanephric collecting ducts indicates that intercalated cells may be present and functioning in both organs. Thus, the lineage of intercalated cells may be more intricate than previously believed.
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PMID:Developmental expression of acid-base-related proteins in the rabbit kidney. 813 Jan 11

The plasma membrane composition of virtually all eukaryotic cells is maintained and continually modified by the recycling of specific protein and lipid components. In the kidney collecting duct, urinary acidification and urinary concentration are physiologically regulated at the cellular level by the shuttling of proton pumps and water channels between intracellular vesicles and the plasma membrane of highly specialized cell types. In the intercalated cell, hydrogen ion secretion into the urine is modulated by the recycling of vesicles carrying a proton pumping ATPase to and from the plasma membrane. In the principal cell, the antidiuretic hormone, vasopressin, induces the insertion of vesicles that contain proteinaceous water channels into the apical cell membrane, thus increasing the permeability to water of the epithelial layer. In both cell types, 'coated' carrier vesicles are involved in this process, but whereas clathrin-coated vesicles are involved in the endocytotic phase of water channel recycling, the transporting vesicles in intercalated cells are coated with the cytoplasmic domains of the proton pumping ATPase. By a combination of morphological and functional techniques using FITC-dextran as an endosomal marker, we have shown that recycling endosomes from intercalated cells are acidifying vesicles but that they do not contain water channels. In contrast, principal cell vesicles that recycle water channels do not acidify their lumens in response to ATP. These non-acidic vesicles lack functionally important subunits of the vacuolar proton ATPase, including the 16 kDa proteolipid that forms the transmembrane proton pore. Because these endosomes are directly derived via clathrin-mediated endocytosis, our results indicate that endocytotic clathrin-coated vesicles are non-acidic compartments in principal cells. In contrast, recycling vesicles in intercalated cells contain large numbers of proton pumps, arranged in hexagonally packed arrays on the vesicle membrane. These pumps are inserted into the apical plasma membrane of A-type (acid-secreting) intercalated cells, and the basolateral plasma membrane of B-type (bicarbonate-secreting) cells in the collecting duct. Both apical and basolateral targeting of H(+)-ATPase-containing vesicles in these cells may be directed by microtubules, because polarized insertion of the pump into both membrane domains is disrupted by microtubule depolymerizing agents. However, the basolateral localization of other transporting proteins in intercalated cells, including the band 3-like anion exchanger and facilitated glucose transporters, is not affected by microtubule disruption.
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PMID:Endosomal pathways for water channel and proton pump recycling in kidney epithelial cells. 814 5

In normal rabbit, immunolabeling of intercalated cells in the outer medullary collecting duct (OMCD) demonstrates band 3-like protein in the basolateral plasma membrane (15) and H(+)-adenosinetriphosphatase (H(+)-ATPase) in the apical plasma membrane and cytoplasmic vesicles (30). However, in type A intercalated cells in the cortical collecting duct (CCD), band 3-like protein is located primarily in multivesicular bodies and cytoplasmic vesicles (15), whereas H(+)-ATPase is present in cytoplasmic vesicles only in most intercalated cells (30). In this study, we observed the effect of chronic acid loading on immunolocalization of these transporters in the collecting duct. Adult New Zealand White rabbits received either normal tap water (controls) or 75 mM NH4Cl for 12 days plus eight daily gavages of 2-6 meq NH4Cl/kg body wt. At time of death, mean urine pH of acid-loaded animals was 5.96 (SD = 0.69), vs. 8.47 (SD = 0.07) in controls. Kidneys were fixed by in vivo perfusion and processed for light and electron microscopic immunoperoxidase localization of band 3-like protein and immunogold localization of H(+)-ATPase. In controls, band 3-like protein was largely confined to multivesicular bodies in the majority of positive-staining intercalated cells in the CCD and to the basolateral plasma membrane of intercalated cells in the OMCD. In acid-loaded rabbits, band 3 protein-positive intercalated cells in the inner CCD and the in the outer stripe of the OMCD (OMCDo) were strikingly stellate in form. Basolateral plasma membrane label was intensified, while the number of labeled multivesicular bodies was diminished. Morphometric analysis demonstrated an increase in the amount of basolateral plasma membrane in these intercalated cells. In control rabbits, H(+)-ATPase immunoreactivity in intercalated cells in the CCD was located predominantly over cytoplasmic vesicles. A minority of intercalated cells exhibited basolateral plasma membrane label, and only an occasional cell displayed apical plasma membrane label. In acid-loaded rabbits, H(+)-ATPase immunoreactivity was enhanced along the apical plasma membrane of intercalated cells in the inner CCD, and morphometric analysis demonstrated increased apical plasma membrane in band 3-positive intercalated cells in this segment. These results suggest that rabbits respond to acid loading via enhancement of both electrogenic proton secretion and Cl-/HCO3- exchange in intercalated cells in the inner CCD and the OMCDo.
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PMID:Activation of acid-secreting intercalated cells in rabbit collecting duct with ammonium chloride loading. 818 97

Previous pharmacologic and kinetic studies have demonstrated the axial heterogeneity of the rabbit kidney tubule with regard to Na,K-ATPase. To evaluate whether this heterogeneity might reflect the presence of distinct isoforms of the alpha subunit of Na,K-ATPase, we used two monoclonal antibodies, IIC9 and IIE2 (G8), specific for the alpha 1 and alpha 3 isoforms, respectively, as probes for changes in the specific activity of Na,K-ATPase at the level of successive segments of the rabbit nephron. Single, well defined nephron segments were obtained by microdissection of collagenase-treated kidney. Results indicate that IIC9 antibody inhibited Na,K-ATPase activity by > 90% in all the segments of the nephron except the collecting duct. Conversely, IIE2 (G8) antibody abolished Na,K-ATPase activity in the collecting duct, whereas it had no effect in other nephron segments. These findings suggest that the rabbit collecting duct preferentially expresses a distinct isoform of Na,K-ATPase catalytic subunit, which is presumably alpha 3-like, in agreement with previous pharmacologic and kinetic observations, whereas other nephron segments would express the alpha 1 isoform.
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PMID:Are there several isoforms of Na,K-ATPase alpha subunit in the rabbit kidney? 838 54

At least two populations of intercalated cells, type A and type B, exist in the connecting tubule (CNT), initial collecting tubule (ICT), and cortical collecting duct (CCD). Type A intercalated cells secrete protons via an apical H+-ATPase and reabsorb bicarbonate by a band 3-like Cl-/HCO3-exchanger, AE1, located in the basolateral plasma membrane. Type B intercalated cells secrete bicarbonate by an apical Cl-/HCO3- exchanger that is distinct from AE1 and remains to be identified. They express H+-ATPase in the basolateral plasma membrane and in vesicles throughout the cytoplasm. A third type of intercalated cell with apical H+-ATPase, but no AE1, has been described in the CNT and CCD of both rat and mouse. The prevalence of the third cell type is not known. The aim of this study was to characterize and quantify intercalated cell subtypes, including the newly described third non A-non B cell, in the CNT, ICT, and CCD of the rat and mouse. A triple immunolabeling procedure was developed in which antibodies to H+-ATPase and band 3 protein were used to identify subpopulations of intercalated cells, and segment-specific antibodies were used to identify distal tubule and collecting duct segments. In both rat and mouse, intercalated cells constituted approximately 40% of the cells in the CNT, ICT, and CCD. Type A, type B, and non A-non B intercalated cells were observed in all of the three segments, with type A cells being the most prevalent in both species. In the mouse, however, non A-non B cells constituted more than half of the intercalated cells in the CNT, 39% in the ICT, and 22% in the CCD, compared with 14, 7, and 5%, respectively, in the rat. In contrast, type B intercalated cells accounted for only 8 to 16% of the intercalated cells in the three segments in the mouse compared with 26 to 39% in the rat. It is concluded that striking differences exist in the prevalence and distribution of the different types of intercalated cells in the CNT, ICT, and CCD of rat and mouse. In the rat, the non A-non B cells are fairly rare, whereas in the mouse, they constitute a major fraction of the intercalated cells, primarily at the expense of the type B intercalated cells.
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PMID:Intercalated cell subtypes in connecting tubule and cortical collecting duct of rat and mouse. 989 Mar 3

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