Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influence of several parameters on the kinetics of activation of the progesterone receptor in the cytosol of rabbit uterus is described. The estimation of the proportion of activated receptor is based on the differential affinity of the activated and non-activated forms of the receptor for phosphocellulose. Under appropriate conditions binding to phosphocellulose can be used as a test of activation and gives results similar to those obtained with DNA--cellulose, or isolated cell nuclei. The kinetics of receptor activation is temperature-dependent and compatible with a first-order reaction at all temperatures tested. The thermodynamic activation energy of this reaction is 67.8 kcal mol-1. The progesterone receptor can be activated to various extents by increased ionic strength or by dilution of the cytosol with buffers of low ionic strength, and in all cases the activation follows apparent first order kinetics. At a concentration of 0.4 M NaCl, 70--80% of the receptor can be converted into the activated form. The activated and non-activated forms of the receptor appear to be in equilibrium. Salt-activated and heat-activated receptor can be transformed to a non-activated form by decreasing either the salt concentration, or the temperature of incubation. The rate of dissociation of the steroid from the activated form of the receptor is indistinguishable from that observed with the non-activated form, but the activated receptor is more thermolabile. Upon centrifugation on sucrose gradients there are no major differences in the sedimentation behaviour of the two forms of the receptor.
Mol Cell Endocrinol 1979 Dec
PMID:Activation of the progesterone receptor of rabbit uterus. 52 Jun 62

Physical and chemical considerations permit the division of the near-surface regolith on Mars into at least six zones of distinct microenvironments. The zones are euphotic, duricrust/peds, tempofrost, permafrost, endolithic, and interfacial/transitional. Microenvironments vary significantly in temperature extremes, mean temperature, salt content, relative pressure of water vapor, UV and visible light irradiance, and exposure to ionizing radiation events (100 Mrad) and oxidative molecular species. From what is known of the chemistry of the atmosphere and regolith fines (soil), limits upon the aqueous chemistry of soil pastes may be estimated. Heat of wetting could reach 45 cal/g dry soil; initial pH is indeterminate between 1 and 10; ionic strength and salinity are predicted to be extremely high; freezing point depression is inadequate to provide quantities of liquid water except in special cases. The prospects for biotic survival are grim by terrestrial standards, but the extremes of biological resiliency are inaccessible to evaluation. Second-generation in situ experiments which will better define Martian microenvironments are clearly possible. Antarctic dry valleys are approximations to Martian conditions, but deviate significantly by at least half-a-dozen criteria.
J Mol Evol 1979 Dec
PMID:Chemical and physical microenvironments at the Viking landing sites. 52 49

The three-dimensional crystal structure of bovine trypsinogen at approximately pH 7.5 was initially solved at 2.6 A resolution using the multiple isomorphous replacement method. Preliminary refinement cycles of the atomic coordinates trypsinogen have been carried out first to a resolution of 2.1 A, and later to 1.9 A, using constrained difference Fourier refinement; During the process, structure factors Fc and phi c were calculated from the trypsinogen structure and final interpretation was based on an electron-density map computed with terms (2 Fo - Fc) and phases phic at a resolution of 1.9 A. Crystals of trypsinogen grown from ethanol-water mixtures are trigonal with space group P3121, and cell dimension a = 55.17 A and c = 109.25 A. The structure is compared with the bovine diisopropylphosphoryltrypsin structure at approximately pH 7.2, oirginally determined from orthohombic crystals by Stroud et al. (Stroud, R.M., Kay L.M., and Dickerson, R.E. (1971), Cold Spring Harbor Symp. Quant. Biol. 36, 125-140; Stroud, R.M., Kay, L.M., and Dickerson, R.E. (1974), J. Mol. Biol. 83, 185-208), and later refined at 1.5 A resolution by Chambers and Stroud (Chambers, J.L., and Stroud, R.M. (1976), Acta Crystallogr. (in press)). At lower pH, 4.0-5.5 diogen, with cell dimensions a = 55.05 A and c = 109.45 A. This finding was used in the solution of the six trypsinogen heavy-atom derivatives prior to isomorphous phase analysis, and as a further basis of comparison between trypsinogen and the low pH trypsin structure. There are small differences between the two diisopropylphosphoryltrypsin structures. Bovine trypsinogen has a large and accessible cavity at the site where the native enzyme binds specific side chains of a substrate. The conformation and stability of the binding site differ from that found in trypsin at approximately pH 7.5, and from that in the low pH form of diisopropylphosphoryltrypsin. The catalytic site containing Asp-102, His-57, and Ser-195 is similar to that found in trypsin and contains a similar hydrogen-bounded network. The carboxyl group of Asp-194, which is salt bridged to the amino terminal of Ile-16 in native trypsin or other serine proteases, is apparently hydrogen bonded to internal solvent molecules in a loosely organized part of the zymogen structure. The unusually charged N-terminal hexapeptide of trypsinogen, whose removal leads to activation of the zymogen, lies on the outside surface of the molecule. There are significant structural changes which accompany activation in neighboring regions, which include residues 142-152, 215-550, 188A-195. The NH group of Gly-193, normally involved in stabilization of reaction intermediates (Steitz, T.A., Henderson, R., and Blow, D.M. (1969), J. Mol. Biol. 46, 337-348; Henderson, R. (1970), J. Mol. Biol. 54, 341-354; robertus, J.D., Kraut, J., Alden, R.A., and Birkoft, J.J. (1972), Biochemistry 11, 4293-4303) in the enzyme, is moved 1.9 A away from its position in trypsin...
 ...
PMID:Structure of bovine trypsinogen at 1.9 A resolution. 55 51

An in vivo and in vitro study was carried out on the prostate from the female Praomys (Mastomys) natalensis to identify and characterize the binding of androgens within the cytoplasm. The labelled cytosol was prepared and subjected to gel exclusion chromatography and density gradient centrifugation. A macromolecular protein associated with the radioactivity was isolated on Sephadex G-200. Subsequent analysis of the steroid receptor complex showed that the major part of the radioactive steroid (64 percent) was dihydrotestosterone. This binding was inhibited by unlabelled testosterone and could not be demonstrated in liver cytosol. Characterization of this dihydrotestosterone receptor complex revealed a sedimentation coefficient of 4.6 s in the presence of a high salt solution (0.4 M KCl). The complex aggregated in the absence of 0.4 M KCl and sedimented preferentially from 5.6-7.4 s together with polydisperse aggregates of higher sedimentation coefficients. The use of this animal as an experimental model for hormonal studies on the prostate is suggested.
Mol Cell Endocrinol 1977 Aug
PMID:Identification of an androgen receptor in the cytosol of the female Mastomys prostate. 56 99

Electrophoretic mobility, amino acid composition and salt dissociation of histones isolated from sperm of sea urchin Strongylocentrotus intermedius and calf thymus cells were studied. The special arginine-rich histone fraction (I) has been observed in sea urchin sperm chromatin, this fraction being absent in calf thymus chromatin. Dissociation of lysine-containing histone fractions from sea urchin chromatin occured in the range of 0.7 to 1.0 M NaCl concentrations. H1 of calf thymus chromatin was totally extracted with 0.6 M NaCl. In the course of a further increase of salt concentrations (up to 1.5 M NaCl) a practically total extraction of histones from sperm chromatin was observed, while about 20% of proteins remained bound to DNA in thymus chromatin after extraction with 2.0 M NaCl. The template activity of non-extracted DNP preparations from urchin sperm was equal to 2-3% of that of totally deproteinized DNA. The template activity of DNP gradually increased at protein extraction from DNP preparations. The hybridization capacity of RNA transcribed on partially dehistonized DNP templates in vitro also increased.
Mol Biol (Mosk)
PMID:[Sea urchin sperm DNP. I. Chemical composition and template properties of DNP]. 56 76

Estrogens stimulate prolactin (PRL) synthesis by GH3 cells, a clonal strain of rat pituitary cells grown in culture. At 4 degrees C the binding of [3H]17 beta-estradiol to monolayer cultures of GH3 cells was specific and of limited capacity, with half-maximal and maximal binding after 1--2 h and 12 h, respectively. Scatchard analysis showed one single class of binding sites with Kd = 3.1 X 10(-10) M and n = 309 X 10(-15) mol 17 beta-estradiol/mg cell protein, calculated to give approx. 25,000 binding sites per cell. At 4 degrees C less than 10% of the specifically bound [3H]17 beta-estradiol was found in the nuclear fraction. When the incubation temperature was raised to 37 degrees C, the amount of radioactivity in the nucleus increased to 25% within 30 min with a corresponding reduction in the cytoplasm. The cytosol fractions from monolayer cultures as well as from tumors of GH3 cells contained specific 17 beta-estradiol binding proteins, having a sedimentation constant close to 8S in a salt-free buffer and 4S in the presence of 0.5 M KCl. scatchard analysis showed one single class of binding sites with Kd = 3.6 X 10(-10) M and n = 258 X 10(-15) mol 17 beta-estradiol/mg cytosol protein (GH3 tumor tissue). Thus, GH3 cells grown in culture and in the intact animal have similar binding characteristics as judged from the data for binding affinity, capacity and specificity. After the in vivo administration of [3H]17 beta-estradiol to GH3 tumor-bearing rats, radioactivity could be extracted (0.5 M KCl) from purified nuclei bound to 4.5S macromolecules. We suggest that the action of 17 beta-estradiol on GH3 cells involves an initial binding of the steroid to specific receptors in the cytoplasm, followed by transport of a fraction of the hormone-receptor complexes to the nucleus involving a temperature-sensitive step.
Mol Cell Endocrinol 1978 Oct
PMID:Receptors for 17beta-estradiol in prolactin-secreting rat pituitary cells. 56 89

An ethidium homodimer and acridine ethidium heterodimer have been synthesized (Gaugain, B., Barbet, J., Oberlin, R., Roques, B. P., & Le Pecq, J. B. (1978) Biochemistry 17 (preceding paper in this issue)). The binding of these molecules to DNA has been studied. We show that these dimers intercalate only one of their chromophores in DNA. At high salt concentration (Na+ greater than 1 M) only a single type of DNA-binding site exists. Binding affinity constants can then be measured directly using the Mc Ghee & Von Hippel treatment (Mc Ghee, J. D., & Von Hippel, P. H. (1974) J. Mol. Biol. 86, 469). In these conditions the dimers cover four base pairs when bound to DNA. Binding affinities have been deduced from competition experiments in 0.2 M Na+ and are in agreement with the extrapolated values determined from direct DNA-binding measurements at high ionic strength. As expected, the intrinsic binding constant of these dimers is considerably larger than the affinity of the monomer (ethidium dimer K = 2 X 10(8) M-1; ethidium bromide K = 1.5 X 10(5) M-1 in 0.2 M Na+). The fluorescence properties of these molecules have also been studied. The efficiency of the energy transfer from the acridine to the phenanthridinium chromophore, in the acridine ethidium heterodimer when bound to DNA, depends on the square of the AT base pair content. The large increase of fluorescence on binding to DNA combined with a high affinity constant for nucleic acid fluorescent probes. In particular, such molecules can be used in competition experiments to determine the DNA binding constant of ligands of high binding affinity such as bifunctional intercalators.
 ...
PMID:DNA Bifunctional intercalators. 2. Fluorescence properties and DNA binding interaction of an ethidium homodimer and an acridine ethidium heterodimer. 56 95

Highly purified poly(A)-containing free and polysomal mRNP particles have been isolated by chromatography of subcellular fractions of chick embryonic muscles on oligo-dT-cellulose and elution with low salt buffer at 45 degrees. The free and polysomal mRNP represent two distinct classes of macromolecules, the free particles having a more complex nucleoprotein organization than the polysomal particles. Comparison of the protein moieties of three classes of poly(A)-containing cytoplasmic mRNP -- those released from nuclei after in vitro transcription and processing (transported mRNP), the free, and polysomal mRNP -- strongly suggests that the majority of the mRNA-associated proteins are exchanged in the cytoplasm during the various functional states of mRNA. A model of translational control involving the participation of mRNA-associated proteins in chick embryonic muscles and by analogy in other differentiated eukaryotic cells is proposed.
Mol Biol Rep 1979 May 31
PMID:A model of translational control involving mRNA-associated proteins in chick embryonic muscles. 57 74

1. Acute chloride depletion, without sodium depletion, was produced in rats by a single exchange peritoneal dialysis against sodium bicarbonate solution. Blood volume was restored after dialysis by infusion of salt-free albumin, and exogenous deoxycorticosterone and antidiuretic hormone were given. 2. Clearance studies in the period (3 h) after dialysis revealed no difference in the glomerular filtration rate or in the filtered sodium load between experimental and control rats but urinary sodium concentrations and absolute and fractional sodium excretion were significantly higher in the chloride-depleted group. 3. There was also a significant kaliuresis, increased urinary flow rate and diminished free water reabsorption. Urinary bicarbonate excretion increased to a variable degree but the major rise in anion excretion was 'unmeasured' (Na+ + K+ - [Cl- + HCO3- + PO4(3-)]). 4. It is postulated that chloride depletion imposes limitations on sodium reabsorption in the ascending limb of the loop of Henle.
Clin Sci Mol Med 1977 Jan
PMID:Natriuresis in rats acutely depleted of chloride. 60 61

Polysomal preparations from isolated pumpkin cotyledons treated with cytokinin [6-benzylaminopurine (BAP), 10 mg/l] were about two-fold more active in the cell-free system of protein synthesis as compared to polysomes from control cotyledons. The time course of 14C-leucine incorporation into protein and its dependence on polysome concentration were studied; sucrose density fractionation have revealed significant differences in polysome distribution between the treated and control cotyledons. All polysomal fractions from BAP-treated cotyledons were more active in protein synthesis than corresponding fractions from control cotyledons. Mixing of BAP-treated and untreated cotyledons before polysome isolation showed that the difference in their activity did not result from isolation procedure. Factors of polysome activation and/or inhibition were tightly bound to polysomes. Treatment of polysomes with 0.175 M KCl reduced markedly their protein-synthesizing activity and abolished the difference between polysomes of BAP-treated and control cotyledons. The initial level of polysome activity could be restored by addition of proteins isolated from the salt wash, but these proteins were not specific in their action. Possible mechanisms of phytohormone action on ribosome activity are discussed. BAP activation of ribosomes in protein synthesis in vitro is fully eliminated by addition of natural inhibitor--abcisic acid--to BAP solution during cotyledons incubation.
Mol Biol (Mosk)
PMID:[Effect of 6-benzylaminopurine on (14C)leucine incorporation into protein in a cell-free system from isolated squash cotyledons]. 61 29


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>