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)

hCG is a known stimulator of mouse thyroid in vivo. Studies were therefore performed to ascertain whether the thyroid-stimulating activity of hCG in the mouse could also be demonstrated by the in vitro techniques that had failed to show any activity of hCG in the human thyroid. When labeled with 125I and incubated at 22 degrees C in 20 mM Tris-0.5% bovine serum albumin (Tris-BSA), pH 7.45, with increasing concentrations (70-300 micrograms protein/ml) of a mouse thyroid fraction, a purified hCG preparation [( 125I]hCG) showed 5-12% specific binding. In contrast, its binding to a human thyroid particulate fraction, over the same range of protein concentrations, did not exceed 1%. When similar studies were performed at 37 degrees C in 10 mM Tris-50 mM NaCl-0.5% BSA, pH 7.45, [125I]hCG showed no detectable binding either to the human or the mouse thyroid fractions. At concentrations ranging from 1 to 20 mIU/ml (0.9-18 X 10(-9) M), bTSH stimulated cAMP release from human thyroid slices into the medium in a dose-dependent manner. In contrast, hCG concentrations from 10(3) to 10(4) IU/ml (2-20 X 10(-6) M) were without effect on cAMP release. bTSH, at concentrations of 4.5 and 9.0 mIU/ml (4 and 8 X 10(-9)M), stimulated cAMP release from the mouse thyroid, producing in the medium approximately 11- and 28-fold increases in cAMP concentration. hCG also stimulated cAMP release from the mouse thyroid, the increases being approximately 2.3- and 1.8-fold, in the presence of 2270 and 4540 IU/ml (4.5 and 9.0 X 10(-6) M), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Endocrinol 1985 Jan
PMID:Divergent responses by human and mouse thyroids to human chorionic gonadotropin in vitro. 298 77

The statistical segment length of duplex DNA was determined in phage T4 ligase (poly(deoxyribonucleotide): poly(deoxyribonucleotide) ligase (AMP forming), EC 6.5.1.1) buffer (50 mM-Tris . HCl (pH 7.8), 20 mM-dithiothreitol, 10 mM-MgCl2, 1 mM-ATP) at 12 degrees C to be 1030(+/- 116) A. This result was obtained by electron microscopic examination of the molecular distributions generated by T4 ligase-mediated joining of EcoRI-cleaved pBR322 DNA. This value of the statistical segment length was utilized in an extension of the Jacobson-Stockmayer theory on the probability of intramolecular cyclization in order to optimize DNA joining reactions that are of great utility in recombinant DNA experiments. Five cloning systems were analyzed: circular plasmid vectors that had been linearized with one or two restriction endonucleases, circular plasmids that had been tailed with deoxyhomopolymers before joining, lambda-type cloning vectors and cosmids. The results are tabulated for convenient use in molecular cloning experiments.
J Mol Biol 1985 Jan 20
PMID:Analysis and optimization of recombinant DNA joining reactions. 298 33

A binding site for the thromboxane A2/prostaglandin H2 (TXA2/PGH2) antagonist 125I-PTA-OH (9,11-dimethylmethano-11,12-methano-16-(4-methoxyphenyl)-13,14-dih ydro-13-aza-1 5 alpha beta-w-tetranor-TXA2) to washed canine platelets is described. 127I-PTA-OH competitively antagonized aggregation induced by the TXA2/PGH2 mimetic U46619. A Schild analysis of the pharmacologic study revealed pA2 of 7.97 and a slope of -0.95. The pA2 value yielded a Kd of 11 nM. Specific binding in Tris-NaCl buffer (pH 7.4) is not affected by extracellular Ca2+ or Mg2+ in concentrations up to 750 microM. The pH optimum for binding resides between 7.0 and 7.4. The association rate constant, k1, was 4.5 X 10(6) M-1 min-1, and the dissociation rate constant, k-1, was 1.45 X 10(-1) min-1, yielding a kinetically determined Kd (k-1/k1) of 32 nM. Scatchard analysis of I-PTA-OH binding to washed canine platelets revealed two classes of binding sites, a high affinity site (Kd = 24 nM, Bmax = 71 fmol/10(7) platelets) (4400 binding sites/platelet) and a low affinity site (Kd = 2.1 microM). Several TXA2/PGH2 receptor antagonists competed with specific 125I-PTA-OH binding, and the rank order of potency for displacing the ligand correlated (r = 0.97) with the rank order of potency for their ability to inhibit U46619-induced aggregation in canine platelet-rich plasma. Prostaglandins F2 alpha and E2 also displaced the ligand, but only at much higher concentrations. Binding of I-PTA-OH or the TXA2/PGH2 mimetic U46619 was unaffected by the aggregating agents epinephrine (10 microM) or ADP (5 microM). The similarity in the Kd values obtained kinetically, by equilibrium binding studies for the high affinity site and by Schild analysis, suggests that this high affinity site mediates TXA2/PGH2 induced platelet aggregation. In addition, the close correlation between the abilities of the antagonists to displace the ligand and to inhibit U46619-induced aggregation suggests that this site may represent a TXA2/PGH2 receptor.
Mol Pharmacol 1985 Aug
PMID:Binding of an 125I-labeled thromboxane A2/prostaglandin H2 receptor antagonist to washed canine platelets. 299 36

A cardiac muscle sarcolemmal preparation, enriched in adenylate cyclase, Na+, K+ -ATPase, beta, muscarinic and ouabain receptors, also contained endogenous protein kinase activity. Phosphorylation of sarcolemmal membrane proteins by the endogenous protein kinase occurred mainly on 22 000 and 12 000 Mr proteins. To determine the effect of this phosphorylation on sarcolemmal properties, sarcolemmal vesicles were preincubated under conditions for optimal phosphorylation while control vesicles were preincubated under identical conditions but in the absence of ATP to avoid phosphorylation. Both control and phosphorylated vesicles were centrifuged, resuspended in 10 mM Tris-Cl (pH 7.4) and subsequently assayed for ATPase activities and for binding of ouabain, dihydroalprenolol and quinuclidinyl benzilate to the membranes. Sarcolemmal phosphorylation was associated with an increase in Ca2+ -ATPase activity but had no effect on Mg2+ ATPase or Na+, K+ -ATPase activity or on ouabain binding. Muscarinic receptor and beta-adrenoreceptor binding also appeared to be unaffected.
J Mol Cell Cardiol 1985 Nov
PMID:Influence of protein kinase phosphorylation on isolated sarcolemmal membranes. 300 20

We have recorded the C-2 proton resonances of the histidines of carbonmonoxyhaemoglobin A and of four abnormal human HbCOs in different buffers and at different concentrations of haemoglobin. Resonance H assigned by Perutz et al. (1985) to His HC3(146) beta, is present at both pH 7.30 and pH 6.90, but somewhat broadened when recorded in 5 to 10% HbCO A in 0.1 M-bis-Tris. The broadening disappears on tenfold dilution of the Hb with bis-Tris and the resonance then stands out sharply. Resonance H is absent at both Hb concentrations in HbCO Cowtown (His HC3(146) beta----Leu). HbCO Fort de France (His CD3(45) alpha----Arg) in 0.1 M-bis-Tris of pH 6.90 has a spectrum similar to that of HbCO A. In the same buffer a resonance marked L by Russu et al. (1982) is absent from the spectrum of Hb Abbruzzo (His H21(143) beta----Arg), whereas resonance H is present. Hb Barcelona contains an additional histidine in position FG1(94) beta; in 0.1 M-bis-Tris buffer of pH 6.90 its resonance is not resolved and resonance H is either shifted or broadened. The resonances of both histidines are resolved in phosphate buffer. At pH 6.90, spectra in 0.1 M-bis-Tris buffer are similar to those previously recorded in 0.2 M-HEPES. Addition of 0.1 M-KCl produces marked changes. Replacement of bis-Tris by 0.2 M-KCl + 0.2 M-phosphate gives rise to a different and much better resolved spectrum.
J Mol Biol 1985 Nov 20
PMID:Comparison of histidine proton magnetic resonances of human carbonmonoxyhaemoglobin in different buffers. 300 66

Chromatin structure of globin and ovalbumin genes in chicken erythrocyte nuclei has been investigated by means of the "nuclease criterion" (described earlier). In intact nuclei (i.e. in the presence of 3 mM MgCl2) DNase I cleaves chromatin of both genes generating fragments multiple of a double-nucleosome repeat (2N-periodicity). However, in the case of the globin gene, apart from the 2N-periodicity, fragments were observed that are multiple of 100 b.p. and are characteristic for partially unfolded chromatin. This distinction in nuclease cleavage patterns correlates with a higher sensitivity of the globin gene as compared with the inactive ovalbumin gene. At 0.5-0.7 mM MgCl2 the transition from dinucleosomal fragmentation with DNase I and DNase II to fragmentation via a 100 b.p. interval occurs and the difference in digestibility of both genes is dramatically increased. If chromatin has been decondensed by incubation of nuclei in 10 mM Tris-buffer DNase Il generates an usual nucleosomal repeat, and in this ionic conditions one may not observe any difference in nuclease sensitivity of the analyzed genes. The data allow to suggest that the high nuclease sensitivity of potentially active genes can be conditioned by more relaxed arrangement of nucleosomes in higher order chromatin structure.
Mol Biol (Mosk)
PMID:[Structural state of active and inactive genes during chromatin decondensation]. 318 36

The oxygen dissociation constants from Fe subunits in the half-ligated intermediate states of Fe-Co hybrid hemoglobins, alpha(Fe-O2)2 beta(Co)2 and alpha(Co)2 beta(Fe-O2)2, have been determined as functions of pH, temperature and inositol hexaphosphate. The oxygen dissociation rates from alpha(Fe-O2)2 beta(Co)2 are estimated to be more than 1300 s-1 for the deoxy quaternary state (T-state) and less than 3 s-1 for the oxy quaternary state (R-state) at 15 degrees C in 50 mM-Tris or Bis-Tris buffer containing 0.1 M-Cl-, while those of alpha(Co)2 beta(Fe-O2)2 are more than 180 s-1 and less than 5 s-1 for the T and R-states, respectively. The pH dependence of the oxygen dissociation rate from Fe subunits is large enough to be accounted for by the R-T transition, and implies that those half-ligated intermediate hybrids mainly exist in the R-state at pH 8.8, and in the T-state at pH 6.6, while other studies indicated that the half-ligated hybrids are essentially in the R-state at pH 7. Large activation energies of the oxygen dissociation process of 19 to 31 kcal/mol determined from the temperature dependence suggest that the process is entropy-driven.
J Mol Biol 1988 Oct 20
PMID:Transient kinetics of oxygen dissociation from ferrous subunits of iron-cobalt hybrid hemoglobins. The principal reaction controlling the co-operativity. 321 Feb 38

1. The binding of oxotremorine-M to M1 muscarine receptors was examined by measuring competition between the agonist and 3H-pirenzepine, using rabbit hippocampal membranes suspended in 20 mM Tris buffer containing 1 mM Mn2+. 2. Both ligands interacted with a single class of receptors. The receptors could assume two affinity states for oxotremorine-M, with equal numbers of high-affinity (KH) and low-affinity (KL) sites. 3. KH interconverted reversibly to KL in the absence of divalent cations and interconverted reversibly to a state similar to KL in the presence of guanyl 5'-yl imidodiphosphate. 4. The results are compatible with a model in which a pair of receptor molecules can be stabilized by a guanine nucleotide-binding "G protein" and have one site each of KH and KL affinity.
Cell Mol Neurobiol 1988 Jun
PMID:Two affinity states of M1 muscarine receptors. 340 66

Porfiromycin was reductively metabolized by NADPH cytochrome P-450 reductase and xanthine oxidase under anaerobic conditions. The production of metabolites varied with the pH and the contents of the reaction buffer. In Tris buffer, two major metabolites were produced at pH 7.5 and above, whereas one major metabolite was produced at pH 6.5. The three major metabolites were separated and isolated by HPLC. Identification by californium-252 plasma desorption mass spectrometry showed that the two major metabolites from pH 7.5 were (trans) and (cis)-forms of 7-amino-1-hydroxyl-2-methylaminomitosene and the major metabolite from pH 6.5 was 7-amino-2-methylaminomitosene. All three major metabolites showed substitutions at the C-1 position. DNA was alkylated readily by enzyme-activated porfiromycin. Digestion of porfiromycin-alkylated DNA by DNase, snake venom phosphodiesterase, and alkaline phosphatase resulted in an insoluble nuclease-resistant fraction and a soluble fraction. The nuclease-resistant fraction reflected a high content of cross-linked adducts. Upon HPLC analysis, the solubilized fraction contained two monofunctionally linked porfiromycin adducts and a possibly cross-linked dinucleotide. The major adduct was isolated by HPLC and identified by NMR, as N2-(2'-deoxyguanosyl)-7-amino-2-methylaminomitosene. The N2 position of deoxyguanosine appeared as the major monofunctional alkylating site for DNA alkylation by porfiromycin. Thus, mitomycin C and porfiromycin (which differs from mitomycin C only by the addition of a methyl group to the aziridine nitrogen) share the same enzymatic activating mechanism that leads to the formation of the same types of metabolites and the same specificity of DNA alkylation.
Mol Pharmacol 1988 Aug
PMID:Metabolites and DNA adduct formation from flavoenzyme-activated porfiromycin. 341 25

Circular dichroism (CD) data indicated that fd gene 5 protein (G5P) formed complexes with double-stranded poly(dA.dT) and poly[d(A-T).d(A-T)]. CD spectra of both polymers at wavelengths above 255 nm were altered upon protein binding. These spectral changes differed from those caused by strand separation. In addition, the tyrosyl 228-nm CD band of G5P decreased more than 65% upon binding of the protein to these double-stranded polymers. This reduction was significantly greater than that observed for binding to single-stranded poly(dA), poly(dT), and poly[d(A-T)] but was similar to that observed for binding of the protein to double-stranded RNA [Gray, C.W., Page, G.A., & Gray, D.M. (1984) J. Mol. Biol. 175, 553-559]. The decrease in melting temperature caused by the protein was twice as great for poly[d(A-T).d(A-T)] as for poly(dA.dT) in 5 mM tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl), pH 7. Upon heat denaturation of the poly(dA.dT)-G5P complex, CD spectra showed that single-stranded poly(dA) and poly(dT) formed complexes with the protein. The binding of gene 5 protein lowered the melting temperature of poly(dA.dT) by 10 degrees C in 5 mM Tris-HCl, pH 7, but after reducing the binding to the double-stranded form of the polymer by the addition of 0.1 M Na+, the melting temperature was lowered by approximately 30 degrees C. Since increasing the salt concentration decreases the affinity of G5P for the poly(dA) and poly(dT) single strands and increases the stability of the double-stranded polymer, the ability of the gene 5 protein to destabilize poly(dA.dT) appeared to be significantly affected by its binding to the double-stranded form of the polymer.
 ...
PMID:fd gene 5 protein binds to double-stranded polydeoxyribonucleotides poly(dA.dT) and poly[d(A-T).d(A-T)]. 350 16


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