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

Antidiuretic hormone (ADH) stimulation of toad bladder granular cells rapidly increases the osmotic water permeability (Pf) of their apical membranes by insertion of highly selective water channels. Before ADH stimulation, these water channels are stored in large cytoplasmic vesicles called aggrephores. ADH causes aggrephores to fuse with the apical membrane. Termination of ADH stimulation results in prompt endocytosis of water channel-containing membranes via retrieval of these specialized regions of apical membrane. Protein components of the ADH water channel contained within these retrieved vesicles would be expected to be integral membrane protein(s) that span the vesicle's lipid bilayer to create narrow aqueous channels. Our previous work has identified proteins of 55 (actually a 55/53-kDa doublet), 17, 15, and 7 kDa as candidate ADH water channel components. We now have investigated these candidate ADH water channel proteins in purified retrieved vesicles. These vesicles do not contain a functional proton pump as assayed by Western blots of purified vesicle protein probed with anti-H(+)-ATPase antisera. Approximately 60% of vesicle protein is accounted for by three protein bands of 55, 53, and 46 kDa. Smaller contributions to vesicle protein are made by the 17- and 15-kDa proteins. Triton X-114-partitioning analysis shows that the 55, 53, 46, and 17 kDa are integral membrane proteins. Vectorial labeling analysis with two membrane-impermeant reagents shows that the 55-, 53-, and 46-kDa protein species span the lipid bilayer of these vesicles. Thus the 55-, 53-, and 46-kDa proteins possess characteristics expected for ADH water channel components. These data show that the 55- and 53- and perhaps the 46-, 17-, and 15-kDa proteins are likely components of aqueous transmembrane pores that constitute ADH water channels contained within these vesicles.
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PMID:Quantitation and topography of membrane proteins in highly water-permeable vesicles from ADH-stimulated toad bladder. 183 Apr 55

Studies were carried out to define antigenic characteristics of the rabbit renal collecting duct. Renal papillae of adult rabbits were homogenized, centrifuged, and the 600 X g pellet was extracted with 0.5% Triton X-100 in the presence of 1 M NaCl. The crude extract was fractionated on an anion exchange column (DEAE cellulose). A fraction enriched in acidic proteins that co-purified with a radioactive 150 kd glycoprotein from cultured collecting duct cells (Minuth 1982), was used for immunization of guinea pigs. The antiserum shows the following characteristics as revealed by indirect immunofluorescence on the rabbit kidney: 1) Among all tubular epithelial cells only principal cells of the collecting duct and the connecting tubule cell show immunoreactivity. 2) The antiserum decorates the epithelial-interstitial interface of the whole collecting duct as well as of connecting tubule and thick ascending limb of Henle's loop. 3) There is immunoreactivity of interstitial fibers throughout the kidney. 4) Epithelial cells in a variety of other organs in rabbit did not react with the antiserum. Our data demonstrate an antigenic distinction of both, the connecting tubule cell and the principal cell, discriminating these cells from other tubular epithelial cells including the intercalated cells of the collecting duct system. Furthermore, our findings point to a heterogeneity along the distal nephron with respect to the constituents of the epithelial-interstitial interface.
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PMID:Immunohistochemical localization of a protein fraction derived from rabbit renal papilla. 639 56

Cortical kidney explants from newborn New Zealand rabbits were cultured in Dulbecco's minimum essential medium (DMEM) containing 10% fetal calf serum. Within 24 h the explants formed 'globular bodies' which were completely covered by a monolayered epithelium. The cells were differentiated and resembled collecting duct epithelium. By culturing the globular bodies in Dulbecco's MEM with D-valine instead of L-valine, a monolayer of collecting duct cells was obtained and used for control experiments. For analysis and identification of synthesized glycoproteins, the globular bodies were incubated with various labelled carbohydrates and amino acids, and then fractionated. Glycoproteins secreted into the culture medium were not detected. Cell-associated glycoproteins were found in crude membrane fractions and then extracted with Triton X-100 for column chromatography, SDS-polyacrylamide electrophoresis in 6 M urea, isoelectrofocusing, and two-dimensional electrophoresis. Two prominent glycoproteins containing galactose and glucosamine were synthesized during the spreading of the epithelium, with an apparent molecular weight of 150,000 and 85,000 (SDS-PAGE). The synthesized glycoproteins differ in their content of radioactive glycoprotein precursor and leucine. The 85,000 dalton monomer glycoprotein has an isoelectric point of 3.5 and was identified by two-dimensional electrophoresis.
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PMID:Glycoprotein synthesis of renal collecting duct epithelium cultured as globular bodies. 685 45

Thin cortical kidney explants from newborn New Zealand rabbits were cultured in Dulbecco's MEM containing 10% fetal bovine serum. Within 24 h the explants formed globular bodies which were completely covered by a monolayered epithelium. The cells show polar differentiation and resemble the renal collecting duct epithelium. By culturing the globular bodies in Dulbecco's MEM with D-valine instead of L-valine additionally a monolayer of renal collecting duct cells was obtained. For the study of glycoprotein synthesis the globular bodies and the collecting duct monolayers were incubated with various labelled carbohydrates, protein and collagen precursors and then fractionated into coarse membrane pellets. The synthesized glycoproteins were regained in 600 x g and 12,000 x g coarse membrane fractions and extracted with Triton X 100 buffer for column chromatography and SDS-polyacrylamide electrophoresis in 6 M urea. In addition to a 85,000 d glycoprotein, a carbohydrate rich collagen like protein (apparent molecular weight in column chromatography 200,000 d, in the SDS-polyacrylamide electrophoresis 150,000 d) was found. The 150,000 d glycoprotein incorporates favorably radioactive proline, sulfate, and smaller amounts of lysine, and leucine. Compared to the 85,000 d glycoprotein a double amount of glucosamine and galactose and four fold amount of fucose was detected. The 85,000 d protein has to be ascribed as a usual glycoprotein, in contrast the 150,000 d protein shows an unusual combination of characteristics and has to be considered as a new type of renal glycoprotein.
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PMID:Cell associated glycoproteins synthesized by cultured renal tubular cells. 717 68

Extracellular calcium/polyvalent cation-sensing receptors (CaR) couple to G proteins and contain highly conserved extracellular cysteine residues. Immunoblotting of proteins from rat kidney inner medullary collecting duct endosomes with CaR-specific antibodies reveals alterations in the apparent molecular mass of CaR depending on protein denaturation conditions. When denatured by SDS under nonreducing conditions, CaR migrates as a putative dimeric species of 240-310 kDa. This is twice the predicted molecular mass of the CaR monomer observed after SDS denaturation in the presence of sulfhydryl-reducing agents. In sucrose density gradients, Triton X-100-solubilized CaR sediments as a 220-kDa complex, not explainable by binding of G proteins to CaR monomers. Treatment of Triton-soluble CaR with divalent (Ca2+, Mg2+) and trivalent (Gd3+) metal ion CaR agonists, but not monovalent ions (Na+), partially shifts the electrophoretic mobility of CaR under reducing conditions from a predominantly monomeric to this putative dimeric species on immunoblots in a manner similar to their rank order of functional potency for CaR activation (Gd3+ >> Ca2+ > Mg2+). This Ca2+ effect is blocked by pretreatment with N-ethylmaleimide. We conclude that disulfide bonds present in CaRs mediate formation of dimers that are preserved in Triton X-100 solution. In addition, CaR exposure to Ca2+ induces formation of additional disulfide bonds within the Triton-soluble CaR complex.
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PMID:Disulfide bonds in the extracellular calcium-polyvalent cation-sensing receptor correlate with dimer formation and its response to divalent cations in vitro. 960 61

A novel cDNA encoding a protein kinase (termed PASK) was isolated from rat brain. The PASK catalytic domain was most similar to Ste20-related protein kinases, showing 45.5 and 39.2% amino acid identity with human SOK1 and yeast Sps1, respectively. The amino-terminal noncatalytic domain of 71 amino acids was rich in alanine and proline and contained several proline-alanine repeats. PASK was widely expressed in rat tissues but negligible in liver and skeletal muscle. Immunohistochemical analysis revealed that PASK was localized to a distinct set of cells including neurons, adrenal glomerulosa cells, and transporting epithelia such as epithelial cells of brain choroid plexus, distal tubule and collecting duct of kidney, duct of salivary gland, and parietal cells of stomach. Subcellular fractionation showed that PASK was present in both the cytosol and the Triton X-100-insoluble cytoskeletal fraction in brain.
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PMID:Molecular cloning and characterization of a novel Ste20-related protein kinase enriched in neurons and transporting epithelia. 967 32

Cadmium toxicity to renal cells was investigated in Madin-Darby canine kidney (MDCK) and LLC-PK1 cells as models of the distal tubule/collecting duct and proximal tubule, respectively. Cells were grown on two-compartment filters and exposed to 0.1-50 microM Cd2+. In MDCK cells, Cd2+ was more toxic from the basolateral than from the apical side and dependent on the extracellular Ca2+ concentration. Toxicity was evident within 24 h, as shown by a decrease in transepithelial resistance (TER), reduced proliferation (bromodeoxyuridine incorporation), reduction in ATP concentration, and morphological changes. On confocal microscopy, E-cadherin and alpha-catenin staining patterns indicated interference with the cadherin-catenin complex. LLC-PK1 cells showed a similar toxicity pattern, which was evident at lower Cd2+ concentrations. An increase of E-cadherin and alpha-catenin molecules in the Triton X-100-insoluble fraction was detectable at high Cd2+ concentrations in LLC-PK1 cells but not in MDCK cells. Lactate dehydrogenase release indicated membrane leakage in LLC-PK1 cells. Rhodamine-phalloidin staining, a probe for F-actin filaments, demonstrated alterations of the actin cytoskeleton in both cell lines. In conclusion, cadmium caused ATP depletion and interfered with the cadherin-catenin complex and probably the tight junctions changing renal cell morphology and function.
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PMID:Cadmium is more toxic to LLC-PK1 cells than to MDCK cells acting on the cadherin-catenin complex. 968 16

Conflicting theories on the existence of several renal arginase isoenzymes remain in debate. Because the activity of arginase is high in two embryologically different nephron segments of the Meriones shawi kidney, namely the cortical (CPST) and medullary (OSPST) proximal straight tubule and the outer medullary collecting duct (OMCD), we postulate that these nephron segments may contain different isoforms. Isolated nephron segments were dissected from collagenase-treated kidneys. Tubules were permeabilized with Triton X-100 (0.25%) and incubated with increasing Arg concentrations to characterize the arginase activity. The results were as follows: (1) in OMCD, one arginase isoform (E1), characterized by a high Arg affinity (1.160 mM), was present; (2) in CPST, two arginase isoforms were discovered - one, E1, had a similar Km (1.407 mM) to that found in OMCD whereas the other (E2) had a low affinity for Arg (Km =18.8 mM); and (3) in OSPST, two isoenzymes were present - E1 which had a Km of 1.478 mM and the second isoform that we named E2 which had a Km of 9.07 mM. In addition, arginase located in CPST and OMCD was strongly inhibited by Orn and Lys. The Ki value for Lys varied between 1.635 and 2.288 mM. Therefore, this work demonstrates that two arginase isoforms are present in the kidney of Meriones shawi. Isoform E1 is present in the proximal tubule and the collecting duct whereas isoform E2 is restricted to the proximal tubule.
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PMID:Identification of two arginase isoenzyme activities along the nephron of Meriones shawi. 991 99

Calcium stone crystal attachment to the urinary epithelium plays an essential role in the development of kidney stones by allowing small crystals to be retained in the kidney until they become macroscopic. We among others have described attachment of stone crystals to cultured renal epithelia (Wiessner, J. H., Kleinman, J. G., Blumenthal, S. S., Garancis, J. C., and Mandel, G. S. (1987) J. Urol. 138, 640-643). To isolate protein(s) that may participate in crystal attachment, apical membranes of cultured renal inner medullary collecting duct were biotinylated, the cells were lysed with detergent, the lysate was subjected to hydroxyapatite chromatography, and fractions were incubated with calcium oxalate monohydrate. Electrophoresis of material solubilized from the crystals showed several selectively adsorbed protein bands. A 110-kDa band stained positively for biotin and for glycosides and bound (45)Ca. The amino acid sequence of this band was determined to be that of a protein closely related to rat nucleolin (nucleolin-related protein; NRP). NRP was cloned and sequenced and was 83% homologous with the previously sequenced nucleolar protein nucleolin. Using temperature-induced phase partitioning with Triton X-114, NRP was associated with both the insoluble membrane skeleton pellet and the soluble aqueous phase but not the soluble detergent phase. This association with the membrane skeleton was increased in the presence of calcium. Thus, NRP is associated with the apical membranes of cultured renal tubular cells and is bound to membrane skeletal elements in a calcium-dependent fashion. The physiological role of NRP remains to be determined; however, a pathophysiological role may be that of mediating the attachment to the renal tubular epithelium of calcium stone crystals.
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PMID:Cloning and preliminary characterization of a calcium-binding protein closely related to nucleolin on the apical surface of inner medullary collecting duct cells. 1048 83