Interaction of [3H]-aldosterone with rat kidney plasma membranes

Ozegović, B; Schön, E; Milković, S.

doi:10.1016/0022-4731(77)90088-7

Cited by 9 publications

(3 citation statements)

References 14 publications

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“…Mor phological examination by electron micros copy showed the membrane vesicles free of gross contaminations ( fig. 1), with no notice able difference to the preparation of adult rat plasma membranes (PM) [14], Low relative specific activities (PM/homogenate) of the mitochondrial marker -GLDH (1.1) -and the lysosomal marker -NAGA (0.43) -and high enrichment of the characteristic PM marker enzyme Na-K-ATPase (9.17) pointed out to a highly purified PM fraction isolated from neonatal kidney (table I). The relative specific activities of all three enzymes were the same, both in newborns and in adult rats, Fig.…”

Section: Resultsmentioning

confidence: 99%

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Postnatal Development of Rat Kidney Plasma Membrane Na-K-ATPase

Dobrović-Jenik¹,

Ozegović²,

Milković³

1984

Neonatology

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The postnatal development of the sodium transport mechanism in the rat kidney, as judged by the activity of renal plasma membrane Na-K-ATPase, was studied. Highly purified kidney plasma membranes as verified by electron microscopic and enzyme examinations, were used. Na-K-ATPase activity (μmol Pi/mg protein/h) increases exponentially from 16.9 ± 1.94 found at birth to the mature level of 43.1 ± 2.16 reached at the age of 41 days. This finding paralleled our results of SDS-polyacrylamide gel disc electrophoresis, showing a completely differentiated plasma membrane protein structure at birth, the maturation of which proceeds only as quantitative enrichment of some protein fractions in the further postnatal period.

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Section: Resultsmentioning

confidence: 99%

“…2). While disc elcctropherograms of newborn and adult rats show 11 different protein bands, those of all the other rats (4-60 days old) show [12][13][14][15] bands. The molecular weights of single pro tein fractions, estimated from their electro phoretic mobilities, were in the range of 11,800-280,000 in all age groups.…”

Section: Resultsmentioning

confidence: 99%

Postnatal Development of Rat Kidney Plasma Membrane Na-K-ATPase

Dobrović-Jenik¹,

Ozegović²,

Milković³

1984

Neonatology

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“…Cytochemistry has identified steroid-binding sites on plasma membranes [5]. Evidence has been reported for carrier-mediated uptake of glucocorticoids by plasma-membrane vesicles, used to avoid complications with cytoplasmic components [6][7][8], and binding sites on plasma-membrane vesicles have been reported for oestrogen [9,10], progesterone [11] and aldosterone [12]. Although all of these studies are consistent with a protein-mediated cellular uptake system for steroids, several other reports have questioned the studies and their conclusions.…”

Section: Introductionmentioning

confidence: 99%

Identification of dexamethasone-binding sites on male-rat liver plasma membranes by affinity labelling

Howell

Couraud

Lefebvre

1989

Biochemical Journal

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Binding studies with [3H]dexamethasone identified two binding sites on plasma membranes prepared from the male rat liver, a low-capacity site with a KD of 7.0 nM and a higher-capacity site with a KD of 90.1 nM. Both sites exhibited glucocorticoid responsiveness and specificity for glucocorticoids and progestins. Triamcinolone acetonide, which competes well for the binding of dexamethasone to the cytosolic glucocorticoid receptor, did not compete well for the binding of [3H]dexamethasone to the plasma-membrane binding sites. The binding sites were sensitive to protease and neuraminidase treatment, and resistant to extraction with NaCl, but were extracted with the detergent Triton X-100. As these experiments indicated the presence of plasma-membrane protein components which bind glucocorticoids at physiological concentrations, affinity-labelling experiments with dexamethasone mesylate were conducted. Two peptides were specifically labelled, one at approx. Mr 66,000 and one at Mr 45,000. The Mr-66,000 peptide was not sensitive to glucocorticoids, and was extracted by NaCl, and so did not correspond to either of the sites identified in the dexamethasone-binding studies. The Mr-45,000 entity, on the other hand, resembled the dexamethasone-binding sites in its response to glucocorticoid manipulation of the animal and in its resistance to salt extraction. This peptide was not present in rat serum. Thus we have identified a plasma-membrane peptide which binds dexamethasone. Whether this peptide is involved in transport of the glucocorticoid across the plasma membrane remains to be determined.

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Metabolic and proliferative responses to estrogen by hepatocytes selected for plasma membrane binding‐sites specific for estradiol‐17β

Pietras

Szego

1979

Journal Cellular Physiology

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Hepatocytes were isolated by established procedures from freshly-excised livers of ovariectomized rats. Integrity of the cells was verified by DNA, protein, and calcium contents, and by dye exclusion. The cells also showed progressive increments in oxidation to 14C0, of [26-14Clcholesterol during one to five hours' incubation. Analysis was undertaken of cellular reactivities toward estrogen and the hepatocarcinogen dibutylnitrosamine (DBN).Binding and retention of [3H]estradiol-17/3 (E,P) by isolated liver cells was specific for E2P, saturable, temperature-dependent, and maximal after 30-minute incubation. The apparent dissociation constant for the binding process at 22°C is 2 X M, and the total number of binding-sites at saturation corresponds to approximately 3,400 E,P molecules per liver cell. To probe for steroid binding-sites a t their external surfaces, cells were incubated 30 minutes with mounted 17/3-estradiol-l7-hemisuccinyl:albumin:nylon fibers. The covalentlyimmobilized estrogen (1 ng/mg albumin) was accessible for interaction with antiserum directed against 17~-estradiol-17-hemisuccinyl:albumin. Significant numbers of isolated liver cells were retained by estrogen-derivatized fibers at 22°C after extensive washes. Binding was markedly reduced by incubation at 4°C and by prior exposure to free E,/3 ( X lo-* M), but not to the relatively inert estradiol-17a (E,a). Fiber-bound cells could be dislodged by brief incubation in 150 mOsM saline with 2 X M E,/3 or diethylstilbestrol, but not E,G, cortisol, progesterone, or testosterone, and recovered intact. Cells that had been retained by t h e fibers and those that were not adherent were collected and washed under identical conditions, then plated in serum-free, chemically-defined medium at 37°C. After 72 hours, specific binding of E,P by the fiber-binding cells during 30 minutes' incubation was 2.5-fold that of cells which had not bound the immobilized steroid. Similarly, stimulation of the oxidation to 14C0, of [26-14Clcholesterol by E,/3 was greater in fiber-binding than in non-binding liver cells after three hours' incubation. In the absence of added mitogen, thymidine incorporation into macromolecular form (20 hours), and cell proliferation (48 hours) were significantly greater in fiber-binding cells as compared to non-binding hepatocytes. Moreover, in parallel experiments, when cells were exposed to 1 X lo-' M estrogens or to 1 X M nitrosamines to assess the capacities of these substances to increase basal thymidine incorporation, total DNA, and cell numbers, only those cells with estrogen-binding sites at their surfaces showed significant E,P-and DBN-induced increments in these parameters a s compared with paired controls that had been treated with E 2 a or the noncarcinogen diphenylnitrosamine. These data indicate that the accessibility of hormone-binding components at the plasma membrane may contribute to the capacity of a given liver cell to respond to E,P, as well as to other known hepatocarcinogens.

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Interaction of [3H]-aldosterone with rat kidney plasma membranes

Cited by 9 publications

References 14 publications

Postnatal Development of Rat Kidney Plasma Membrane Na-K-ATPase

Postnatal Development of Rat Kidney Plasma Membrane Na-K-ATPase

Identification of dexamethasone-binding sites on male-rat liver plasma membranes by affinity labelling

Metabolic and proliferative responses to estrogen by hepatocytes selected for plasma membrane binding‐sites specific for estradiol‐17β

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