Sodium-dependent transport by cultured proximal tubule cells

Al-Mahrouq, Hasan A.; Rassier, Mark E.; Douša, Thomas P.; Kempson, Stephen A.

doi:10.1007/bf02388124

Cited by 5 publications

(1 citation statement)

References 15 publications

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“…By using a fluorescent derivative of phenylglyoxal, a 130 kDa protein was labelled in the intestinal BBMV [14]. Other reagents such as N-acetyl[3H]imidazole [15] and azido-NAD [16] identified four (31, 53, 105 and 176 kDa) and two (70 and 97 kDa) protein bands respectively as possible candidates for the Na+/Pi cotransporter. In no instance has a single protein been unambiguously isolated or demonstrated to exhibit Na+-dependent Pi transport activity in a reconstituted system.…”

Section: Introductionmentioning

confidence: 99%

Reconstitution and characterization of a Na+/Pi co-transporter protein from rabbit kidney brush-border membranes

Dębiec

Lorenc

Ronco

1992

Biochemical Journal

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A protein with Na+/Pi co-transporter activity has been extracted from rabbit brush-border membranes with chloroform/methanol and purified by hydroxyapatite chromatography. The protein has been incorporated by the dilution method into liposomes formed from different types and ratios of lipids. The greatest reconstitution has been achieved into liposomes prepared from cholesterol (20%), phosphatidylcholine (20%), phosphatidylethanolamine (30%) and phosphatidylserine (30%) (CH/PC/PE/PS). Pi uptake by these proteoliposomes had the following characteristics: (i) the initial rate was markedly greater in the presence of an inwardly directed Na+ gradient (600 pmol/10 s per mg) than with a K+ gradient (65 pmol/10 s per mg); (ii) maximal uptake was increased 8-fold above the equilibrium value ('overshoot') when a Na+ gradient was applied; (iii) Pi was not merely bound to proteoliposomes but was transported intravesicularly; and (iv) Na(+)-dependent Pi uptake was sensitive to the known phosphate transport inhibitors. This first successful attempt of reconstitution of Na+/Pi transport activity into proteoliposomes led us to isolate and characterize physico-chemically the protein responsible. Its isoelectric point was about 5.8, and urea/SDS gel electrophoresis revealed a broad band of molecular mass ranging from 63 to 66 kDa under both reducing and non-reducing conditions. In the native form, the molecular mass analysed by gel filtration was estimated to be 170 +/- 10 kDa, suggesting that the protein is a polymer, probably stabilized by hydrophobic bonds. Endoglycosidase F treatment decreased the molecular mass to approx. 50 kDa. It is postulated that this acidic glycoprotein might represent a subunit of the intact Na+/Pi co-transporter from rabbit kidney brush-border membranes.

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Section: Introductionmentioning

confidence: 99%

Reconstitution and characterization of a Na+/Pi co-transporter protein from rabbit kidney brush-border membranes

Dębiec

Lorenc

Ronco

1992

Biochemical Journal

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Characterization of pure proximal and heterogeneous distal human tubular cells in culture

Biest

Nouwen

Dromme

et al. 1994

Kidney International

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Modulation of renal Na-Pi cotransport by hormones acting via genomic mechanism and by metabolic factors

Douša

1996

Kidney International

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The renal Na-Pi cotransport is subject to multiple regulatory inputs, such as endocrine, paracrine and intracrine. Among lipophilic, long-acting hormones that act via genomic mechanism, thyroid hormones, calcitriol, all-trans-retinoic acid stimulate, whereas glucocorticoids and estradiol inhibit the rate of Na-Pi cotransport across the brush border membrane of proximal tubules in vivo and/or across apical membrane of renal epithelial cells in vitro. Some findings suggest that these hormones may also influence Na-Pi cotransporter by modification of membrane microenvironment. It should be considered that Na-Pi cotransport can be modulated by lipophilic hormones by non-genomic signaling mechanisms such as sphingomyelin-ceramide pathway, NAD-cyclic ADP-ribose-Ca2+i pathway or by Ca2+ influx. Recent studies outline a basis for the putative intracrine signaling mechanisms that utilize Ca(2+)-releasing nucleotides, cyclic ADP-ribose, and nicotinic acid adenosine dinucleotide phosphate (NAADP), as novel second messengers for regulation of Na-Pi cotransport in response to changes of intermediary metabolic processes: gluconeogenesis, pentose phosphate pathway, polyamines and metabolism of fatty acids.

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Sodium-dependent transport by cultured proximal tubule cells

Cited by 5 publications

References 15 publications

Reconstitution and characterization of a Na+/Pi co-transporter protein from rabbit kidney brush-border membranes

Reconstitution and characterization of a Na+/Pi co-transporter protein from rabbit kidney brush-border membranes

Characterization of pure proximal and heterogeneous distal human tubular cells in culture

Modulation of renal Na-Pi cotransport by hormones acting via genomic mechanism and by metabolic factors

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