Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have reported previously that incubation of the immunopurified transformed hormone-free glucocorticoid receptor with rabbit reticulocyte lysate reconstitutes the receptor complex with hsp90 and that reconstitution is accompanied by concomitant repression of DNA binding activity and regeneration of the steroid binding conformation (Scherrer, L. C., Dalman, F. C., Massa, E., Meshinchi, S., and Pratt, W. B. (1990) J. Biol. Chem. 265, 21397-21400). In this work we further characterize this system by defining the small M(r) components of reticulocyte lysate required for both structural and functional reconstitution of the receptor-hsp90 complex. Reconstitution is ATP-dependent and there is a direct relationship between the extent of hsp90 binding to the receptor and the number of specific steroid binding sites that are generated. Dialysis of reticulocyte lysate inactivates its reconstituting activity. Addition of an ATP-regenerating system or readdition of small M(r) lysate components (in the form of a Centricon C30 filtrate) has little effect, but the presence of both restores full reconstituting activity to dialyzed lysate, as assayed by steroid binding activity and by the binding of hsp90 and hsp70 to the receptor. The small M(r) activity is heat-stable, and it can be completely replaced by NH+4, K+, and Rb+, with K+ producing a maximal effect at the concentration normally present in undialyzed lysate. Na+ and Li+ have no reconstituting activity. This ion selectivity demonstrates that a monovalent cation binding site is involved in receptor heterocomplex reconstitution. It is intriguing that the protein unfoldase (e.g. clathrin uncoating ATPase) activity of hsp70 is known to have a similar monovalent cation dependence, and that under all conditions where hsp90 becomes bound to the receptor, we find that hsp70 is also bound.
...
PMID:Monovalent cation selectivity for ATP-dependent association of the glucocorticoid receptor with hsp70 and hsp90. 162 4

A novel assay to study transcriptional regulation in vivo designated trans-activation-dependent replication (TDR) assay is based on the modulation of a simian virus 40 (SV40)-derived replication system. A mixture of four plasmids (pPARA + pCIS + pTRANS + pREF) is co-transfected into vertebrate cells. After appropriate incubation, the replication of the pPARA plasmid (containing an SV40 origin of replication) is measured with a simple enzymatic test. We demonstrate that the level of replication is dependent on the differential trans-activation of the reporter pCIS (in which SV40 T-antigen is brought under control of the desired promoter) by the specific regulator protein encoded by the pTRANS plasmid. Three advantages make this assay a convenient tool for the systematic analysis of trans-activation in vivo: (1) remarkable sensitivity (higher than conventional assays); (2) rapid sample processing combined with a built-in standard (pREF-plasmid); (3) avoidance of expensive reagents such as freshly radiolabelled probes. We present the application of the TDR assay to the analysis of deletion mutants of the glucocorticoid receptor (GR) and other, GR-based chimeric trans-activators. The results demonstrate that the properties of protein domains are not always additive in a particular chimaera. Further application possibilities of the TDR assay are also discussed.
...
PMID:A novel expression assay to study transcriptional activators. 216 20

To investigate the direct epithelial effects of corticosteroids on renal ion transport, we studied the influence of the pure glucocorticoid agonist RU 28362 and aldosterone on Na+ and K+ transport in primary cultures of immunodissected rabbit cortical collecting duct (CCD) cells. When grown on permeable supports in a steroid-free medium, CCD monolayers exhibited a lumen-negative transepithelial potential difference (PD) of 5.2 +/- 1.07 mV and a short-circuit current (SCC) of 8.54 +/- 2.2 microA/cm2. Transepithelial resistance averaged 660 +/- 49 omega/cm2. The cultures actively reabsorbed Na+ and secreted K+. Both aldosterone and RU 28362 significantly increased PD and SCC; the effects were time and dose dependent. The effect of RU 28362 was completely prevented by the glucocorticoid receptor antagonist RU 486, whereas ZK 91587, a specific mineralocorticoid receptor antagonist, did not block its effect. Both aldosterone and RU 28362 increased the bath-to-lumen concentration ratio of Na+ while lowering that of K+, indicating an increased Na+ reabsorption and K+ secretion. The number of Na(+)-K(+)-ATPase units was significantly enhanced (approximately 2-fold) by both RU 28362 and aldosterone. These results demonstrate that, in cultured CCD cells, not only aldosterone but also a pure glucocorticoid is able to exert mineralocorticoid-like effects, and this latter effect is mediated by glucocorticoid receptors. Because all parameters studied responded similarly to aldosterone and RU 28362, we speculate that in CCD cells glucocorticoids and mineralocorticoids might act by regulating the same gene(s).
...
PMID:Glucocorticoid receptors mediate mineralocorticoid-like effects in cultured collecting duct cells. 222 Nov 5

Specific binding for progesterone has been determined in rat hepatocytes and mouse liver purified plasma membranes. The binding is saturable, reversible and temperature dependent. Two types of binding sites have been characterized in hepatocytes. The first is of high affinity and low binding capacity and the other one is of low affinity and high capacity of binding. In plasma membranes one type of specific binding site only exists. These high affinity sites are different from nuclear progesterone receptor, nuclear glucocorticoid receptor, digitalis receptor of Na+, K(+)-ATPase, transcortine and from corticoid binding sites determined previously in plasma membrane. We also have observed that specific progesterone binding to hepatocytes and plasma membrane is independent from the alpha and beta adrenergic receptors and from P-site adenosine receptor.
...
PMID:Binding of progesterone to specific sites in isolated hepatic cells and purified plasma membrane fraction. 236 14

We have determined the structure of the gene that encodes the alpha 2 isoform of the human Na,K-ATPase. The gene contains 23 exons and spans approximately 25 kilobases. The amino acid sequence of the human alpha 2 isoform deduced from the genomic sequence exhibits 99% identity to the rat alpha 2 isoform. One of the nine amino acid differences between the human and rat sequences occurs at an amino acid position which is known to be involved in species differences in sensitivity of the alpha 1 isoform to cardiac glycosides. Approximately 1500 base pairs of sequence flanking the 5' end of the alpha 2 gene have been determined. This region contains numerous potential AP-1, AP-2, and NF-1-binding sites, a potential Sp1 recognition site, and several sequences that are similar to the glucocorticoid receptor-binding site. The transcription start site was mapped by primer extension and S1 nuclease protection analyses of RNA from human brain, skeletal muscle, and heart. Multiple transcription initiation sites are clustered between residues -104 to -99 relative to the translation initiation codon. A potential TATA box is located 29 base pairs upstream of the first transcription initiation site. Immediately 5' to the apparent TATA box is a 35-base pair polypurine.polypyrimidine tract containing an imperfect mirror repeat which resembles sequences that form triple-stranded structures. Two intragenic DNA probes which detect restriction fragment length polymorphisms associated with the alpha 2 gene have been identified. These probes will be useful in genetic linkage analyses designed to define the possible role of the Na,K-ATPase in certain hereditary disorders.
...
PMID:Characterization of the human Na,K-ATPase alpha 2 gene and identification of intragenic restriction fragment length polymorphisms. 247 73

Current theories of affective disorders do not account for many of the biological markers replicated in patient studies. We link many biological findings in a reasonable physiological relationship, compatible with mechanisms of action of pharmacological and electroshock therapies for depression. We propose that excessive phospholipase-A2 (PLA2) activity disrupts membrane fluidity, composition, and therefore, the activity, of membrane-dependent proteins. Similar disruptions in these proteins are documented in depressed patients and can be accounted for by excessive PLA2 activity. This paradigm accounts for disturbances in the activity of Na-K-ATPase, beta2- and alpha2-adrenergic receptors, MAO, norepinephrine and serotonin uptake, and imipramine binding. Disturbances in other membrane-dependent proteins, tyrosine and tryptophan hydroxylase, can explain the biogenic amine hypothesis. Inhibition of glucocorticoid receptor and TRH receptor binding to their respective ligands by PLA2 may explain patient nonsuppression in the Dexamethasone Suppression Test and poor response in the TRH stimulation test. Physiological regulators of PLA2 activity; calcium, cortisol, estrogen, progesterone, and PGE2 are documented abnormalities in some patients with affective disorders and consistent with excessive PLA2 activity. Thus, postpartum depression and premenstrual tension syndrome may be described in the paradigm. The mechanisms of action of tricyclic antidepressants, lithium, electroconvulsive shock, and some novel antimanic agents can be described in terms of alterations of PLA2 activity. Interestingly, ethanol perturbs membrane fluidity and membrane-bound enzymes in a manner similar to excessive PLA2 activity. A hereditary factor predisposing patients to affective disorders may be a gene defect at either PLA2 or in its regulation.
...
PMID:Are disturbances in lipid-protein interactions by phospholipase-A2 a predisposing factor in affective illness? 256 35

The primary amino acid sequences of proteins that are receptors for estrogen, glucocorticoids, and ouabain were compared with each other using computer programs designed to detect and quantify similarities between proteins. Three regions of similarity between the estrogen receptor (ER) and the glucocorticoid receptor (GR) were identified. On the ER, residues 173-250, 323-395, and 426-458 are similar to residues 409-486, 540-612, and 644-676, respectively, on the GR. The ALIGN computer analysis of these segments on the ER and the GR gave comparison scores that were 16.8, 13.7, and 6.8 standard deviations higher, respectively, than that obtained with a comparison of randomized sequences of these proteins. The probability of getting these scores by chance is less than 10(-60), 10(-40), and 10(-11), respectively. Others have proposed that the segment on the ER and GR that is nearest their amino terminus (e.g. residues 173-250 of the ER) is part of their DNA binding domain and that the other two similar segments on each receptor, which are closer to their carboxy terminus, are part of their steroid binding domain. Here, we present evidence to support both of these hypotheses. First, an Align computer analysis indicates that residues 323-395 of the ER and residues 570-612 of the GR contain a region that is similar to a part of the alpha-subunit of the (Na+ + K+)ATPase that is hypothesized to bind the steroid ouabain. This similarity provides additional support for the proposed location of the steroid binding site on the ER, GR, and (Na+ + K+)ATPase. Second, a computer search of the protein sequence database revealed that protamine, a DNA binding protein, has some similarity to residues 255-281 of the ER, which are thought to be part of the DNA binding domain in the ER. Further, we find that residues 276-281 of the ER contain a structure that has been found at the nucleotide binding domain of some protein kinases. If this region on the ER binds ATP, then it may be involved in phosphorylation/dephosphorylation of the ER, which is thought to be important in its mechanism of action.
...
PMID:Computer-based search for steroid and DNA binding sites on estrogen and glucocorticoid receptors. 302 Nov 26

The purification and properties of a protein serine kinase (PK-P) extracted with Triton X-100 from membranes of bakers' yeast are described. The enzyme is virtually inactive unless either a histone or a heat-stable polypeptide from yeast membranes and Mg2+ are added. Other divalent cations substitute for Mg2+ poorly or not at all; most of them, including Mn2+, inhibit when added in the presence of 5 mM Mg2+. The enzyme is unstable but can be stabilized by addition of 0.1% Triton X-100 and 20% glycerol. The final preparation shows, on silver-stained electrophoresis gels, two major bands (Mr 41,000 and 35,000). According to gel filtration the molecular weight of the active protein is about 75,000. Of the two subunits, only the smaller one appears to be autophosphorylated. In addition to casein, the enzyme phosphorylates several proteins including the H+-ATPase (Mr 100,000) in the yeast plasma membrane. In order to demonstrate the phosphorylation of the ATPase (up to 0.9 equivalents), exposure of the latter to an acid phosphatase was required. Other phosphorylated proteins include mRNA cap-binding protein from mammalian erythrocytes and yeast, a glucocorticoid receptor protein, and a preparation of the guanine nucleotide-binding proteins Gi and Go from brain. A partial purification of a natural activator from yeast plasma membranes is described.
...
PMID:Polypeptide-dependent protein kinase from bakers' yeast. 354 2

Aldosterone-dependent changes in citrate synthase (CS) activity have been used as an index of mineralocorticoid target sites. However, adrenalectomy (ADX) resulted in a fall in activity of CS and several other enzymes in rabbit heart, a tissue with glucocorticoid-but not mineralocorticoid-specific receptors. The enzymes included CS (2.03-1.36 U/mg protein, normal----ADX, P less than 0.001), isocitrate dehydrogenase-NADP+ (1.10-0.80 U/mg, P less than 0.002), isocitrate dehydrogenase-NAD+ (0.034-0.020 U/mg, P less than 0.01), and hydroxymethylglutaryl-CoA lyase (0.072 to 0.035 U/mg, P less than 0.001); in contrast, mitochondrial malate dehydrogenase levels were not significantly reduced by adrenal loss. There was also a decrease after surgery in sarcolemmal Na-K-(17.30-12.31 mumol Pi . mg protein-1 . h-1, P less than 0.002) and Mg-ATPase activities (14.16-12.11 mumol Pi . mg protein-1 . h-1, P less than 0.05). However, ADX did not result in a significant change in heart weight per kilogram body weight or recovery of mitochondrial protein per gram heart. CS was also assayed in hearts from ADX animals following acute (90 min) and chronic (3 day) steroid replacement. Although neither acute intravenous aldosterone (10 micrograms/kg) nor dexamethasone (100 micrograms/kg) increased activity, exposure to multiple subcutaneous injections of either steroid over a 3-day period significantly elevated CS above ADX values. The coordinate changes in the levels of several myocardial enzymes associated with energy metabolism is discussed in terms of an adaptation to chronic alterations in energy demands as opposed to specific mineralocorticoid or glucocorticoid receptor-mediated processes.
...
PMID:Influence of adrenalectomy and steroid replacement on heart citrate synthase levels. 614 77

The effects of single and multiple injections of aldosterone and dexamethasone on renal Na+-K+-ATPase, in vitro renal gluconeogenesis, and urinary electrolyte excretion were examined in adrenalectomized rats in a dose-dependent manner. Single maximal and supramaximal doses of aldosterone (defined by the effect of electrolyte excretion) had no effect on Na+-K+-ATPase or gluconeogenesis. By contrast, a single administration of dexamethasone (in a dose range that increased fasting blood sugar, stimulated renal gluconeogenesis, and had no mineralocorticoid effects) yielded clear-cut activation of Na+-K+-ATPase. Multiple submaximal doses of dexamethasone produced quantitatively similar stimulation of Na+-K+-ATPase and gluconeogenesis. Multiple supramaximal doses of aldosterone stimulated Na+-K+-ATPase and gluconeogenesis, but maximal and submaximal doses of the hormone were without effect. Aldosterone had no effect on hepatic Na+-K+-ATPase or gluconeogenesis. These results suggest that activation of renal Na+-K+-ATPase can be considered a putative glucocorticoid (not mineralocorticoid) effect. Renal Na+-K+-ATPase activation by chronic aldosterone treatment may be mediated by glucocorticoid receptor sites and, hence, may not represent a genuine mineralocorticoid effect.
...
PMID:Regulation of renal Na+-K+-ATPase in the rat by adrenal steroids. 626 47


1 2 3 4 5 6 7 8 9 Next >>

---