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

A general macromolecular partition function is developed in terms of chemical ligand activity, temperature and pressure for systems described by an array of species which are characterized by their state of allosteric conformation and ligand stoichiometry. The effects of chemical ligand binding, enthalpy change, and volume change are treated in a parallel manner. From a broad viewpoint all of these effects can be regarded as specific cases of generalized binding phenomena. This approach provides a general method for analyzing calorimetric and ligand binding experiments. Several applications are given: (1) Thermal scanning data for tRNAphe (P.L. Privalov and V.V. Filimonov, J. Mol. Biol. 122 (1978) 447) are shown to fit a general model with six conformational states. By application of linkage theory it is shown that sodium chloride is expelled as the molecule denatures. (2) The results of calorimetric titrations on the arabinose binding protein (H. Fukada, J.M. Sturtevant and F.A. Quiocho, J. Mol. Biol. 258 (1983) 13193) are shown to fit a simple two-state allosteric model. (3) A thermal binding curve is simulated for an unusual respiratory protein, trout I hemoglobin (B.G. Barisas and S.J. Gill, Biophys. Chem. 9 (1979) 235), in order to illustrate both the similarities and differences between enthalpy and chemical ligand binding processes.
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PMID:Generalized binding phenomena in an allosteric macromolecule. 397 Oct 23

The tetrameric (H3/H4)2 146 base pair (bp) DNA and hexameric (H3/H4)2(H2A/H2B)1 146 bp DNA subnucleosomal particles have been prepared by depletion of chicken erythrocyte core particles using 3 or 4 M urea, 250 mM sodium chloride, and a cation-exchange resin. The particles have been characterized by cross-linking and sedimentation equilibrium. The structures of the particles, particularly the tetrameric, have been studied by sedimentation velocity, low-angle neutron scattering, circular dichroism, optical melting, and nuclease digestion with DNase I, micrococcal nuclease, and exonuclease III. It is concluded that since the radius of gyration of the DNA in the tetramer particle and its maximum dimension are very close to those of the core particle, no expansion occurs on removal of all the H2A and H2B. Nuclease digestion results indicate that histones H3/H4 in the tetramer particle protect a total of 70 bp of DNA that are centrally located within the 146 bp. Within the 70 bp DNA length, the two terminal regions of 10 bp are, however, not strongly protected from digestion. The optical melting profile of both particles can be resolved into three components and is consistent with the model of histone protection of DNA proposed from nuclease digestion. The structure proposed for the tetrameric histone complex bound to DNA is that of a compact particle containing 1.75 superhelical turns of DNA, in which the H3 and H4 histone location is the same as found for the core particle in chromatin by histone/DNA cross-linking [Shick, V. V., Belyavsky, A. V., Bavykin, S. G., & Mirzabekov, A. D. (1980) J. Mol. Biol. 139, 491-517]. Optical melting of the hexamer particle shows that each (H2A/H2B)1 dimer of the core particle protects about 22 base pairs of DNA.
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PMID:Structure of subnucleosomal particles. Tetrameric (H3/H4)2 146 base pair DNA and hexameric (H3/H4)2(H2A/H2B)1 146 base pair DNA complexes. 405 8

Fine specificity of a population of anti-DNA antibodies which bound both ssDNA and dsDNA with apparently equal affinity was studied in two SLE plasma. Sensitivity of DNA binding to increasing sodium chloride concentration indicated that electrostatic interactions occurred between antibody and phosphate moieties of DNA. Secondary nucleic acid structure was important to DNA binding as double-stranded synthetic deoxynucleotide polymers were more effective inhibitors than their substituent single-stranded polymers. Nucleotide bases were also found to play a role in recognition of DNA by these cross-reactive antibodies, as ssDNA binding was sensitive to increasing temperature which caused unstacking of the nucleotide bases. Differing patterns of reactivity with synthetic deoxynucleotide polymers with similar secondary structures but different nucleotide compositions further indicated the importance of nucleotide bases to dsDNA binding by cross-reactive anti-DNA antibodies in SLE plasma.
Mol Immunol 1983 Jun
PMID:Specificity of anti-DNA antibodies in SLE--II. Relative contribution of backbone, secondary structure and nucleotide sequence to DNA binding. 619 29

1. Spontaneous transmitter release was studied at the frog sartorius neuromuscular junction in the presence of a variety of cations before and after treatment with the specific presynaptic neurotoxin, beta-bungarotoxin (beta-BuTX). 2. Treatment with beta-BuTX produced a maintained increase in spontaneous release, as indicated by the miniature end-plate potential (m.e.p.p.) frequency. It was demonstrated that the m.e.p.p. frequency remained dependent on the extracellular calcium concentration. 3. A 30 mM increase in extracellular sodium chloride produced a reversible increase in frequency only after beta-BuTX treatment, indicating that beta-BuTX had increased the permeability of the presynaptic terminal. 4. Furthermore, several divalent cations other than calcium were shown to either maintain or greatly increase the m.e.p.p. frequency after beta-BuTX treatment (before toxin treatment replacement of calcium by these divalent cations produced only small changes in frequency). The relative effectiveness of the divalent cations tested in increasing spontaneous transmitter release after toxin treatment was Co2+ congruent to Ni2+ greater than Mg2+ greater than Ca2+ congruent to Sr2+ greater than Mn2+. The effect of cobalt, which increased the m.e.p.p. frequency 6.5 times after toxin treatment, was studied in detail.
Cell Mol Neurobiol 1982 Dec
PMID:Alterations in spontaneous transmitter release by divalent cations after treatment of the neuromuscular junction with beta-bungarotoxin. 630 1

The opiate agonists [3H]dihydromorphine (DHM, mu-selective ligand), [3H]bremazocine (potent kappa ligand), and [3H]etorphine bound stereospecifically, with high affinity, and reversibly to partially purified 3-(3-cholamidopropyl)dimethylammonio-1-propanesulfonate (CHAPS)-solubilized extract from rat brain membranes. Recoveries of the three binding activities were as follows: [3H]DHM, 47%; [3H]bremazocine, 55%; and [3H]etorphine, 17%. Each ligand exhibited (by Scatchard analysis) binding to a class of high-affinity sites (Kd = 0.8-2 nM). Hill analyses revealed Hill coefficients of n = 1.1-1.3. Many of the properties of solubilized brain opiate receptors are similar to those of membrane-associated opiate receptors. Opiate binding in soluble fractions was inhibited by a variety of protein-modifying agents, including trypsin, proteinase K, and N-ethylmaleimide as well as by heat treatment (60 degrees, 15 min). The relative potencies of a series of opiate narcotic agonists and antagonists in displacing 2 nM [3H]etorphine binding to the CHAPS-solubilized extract was similar to that determined for rat brain homogenates. In contrast, D-Ala2, D-Leu5-enkephalin (DADLE, putative delta-selective ligand) exhibited a much lower affinity for solubilized brain opiate receptors than for the membrane-bound receptors unless assayed in the presence of manganese chloride, sodium chloride, and GTP. Mu agonist binding to solubilized receptors was inhibited relatively selectively by sodium and guanyl nucleotides. These findings lend support to the pharmacological relevance of the solubilized opiate-binding component(s). The pI of the solubilized brain opiate receptor(s) was estimated by liquid isoelectrofocusing to be pH 4. The sizes of the solubilized, prelabeled [3H]etorphine-receptor complex of the solubilized mu and kappa receptor subtypes, as assayed by stereospecific binding of [3H]DHM and [3H]bremazocine binding, respectively, were estimated by molecular exclusion chromatography. The [3H]etorphine-receptor complex migrated as a broad radioactive peak at a position corresponding to a protein of Stoke radius 63 A. A secondary peak of radioactivity was observed at the salt peak. Mu receptor activity chromatographed as two major peaks. The first of these eluted just behind, but significantly separated from, the protein void peak and corresponded to a Stokes radius of 70 A; the second eluted just ahead of the salt peak and corresponded to a radius of less than 20 A. Kappa receptor activity eluted at positions corresponding to macromolecules of 50 A and less than or equal to 20 A. Together, these findings indicate that selective mu and kappa ligands interact with high molecular weight species of somewhat different sizes as well as a lower molecular weight species, which may represent a common subunit that can bind both ligands.
Mol Pharmacol 1983 Sep
PMID:Solubilization and preliminary characterization of mu and kappa opiate receptor subtypes from rat brain. 631 Mar 62

The secondary structure of histones H2B and H3 from calf thymus has been quantitatively studied in heavy water solutions in a wide range of histone concentrations, pD, and concentrations of sodium chloride by an infrared spectroscopy method. Also, the interactions between molecules of different histones in equimolar mixtures H2A-H2B, H2A-H3, H2A-H4, H2B-H3, H2B-H4, H3-H4, and H2A-H2B-H3-H4 have been investigated using the same method. For H2B and H3 conditions favourable for aggregation have been shown to induce the formation of pleated sheet structure. When the pD and concentration of NaCl are in a physiological range, the secondary structure of H2B and H3 contains about 15% of alpha-helix, 4% of parallel pleated sheet structure, 14% of antipatallel pleated sheet structure in H2B and 18% in H3. For mixtures in all cases, except H2A-H4, there is an interaction between molecules of different histones followed by a reduction of the antiparallel pleated sheet structure content. The data on the secondary structure of histones in different states (under self-association, in mixtures, in nucleosomes, and in chromatin) have been discussed and it is suggested that: 1) the secondary structure of histones in chromatin is essentially similar to that in the state of self-association; 2) in the core nucleosome particle the quantity of DNA (in nucleotide pairs), and the quantities of alpha-helix and antiparallel pleated sheet structure (in peptide groups) satisfy the relation 1 : 1 : 1.
Mol Biol (Mosk)
PMID:[Secondary structure of histones in solution]. 631 20

Volume and morphological changes of the squid giant axons in response to hyper- and hypoosmotic media were examined. In hyperosmotic media, which were made by adding sucrose or sodium chloride to the artificial seawater, the axons behaved approximately as ideal osmometers. The fraction of the osmotically inactive volume was less than 0.05. In hypoosmotic media down to half the osmolality of the artificial seawater, intact squid axons did not show significant volume increases. However, following a combined treatment with hyaluronidase and collagenase, the volume of the squid axons increased in these hypoosmotic media. A wrinkled pattern appeared on the surface of the axons while they were in hyperosmotic media containing excess NaCl or KCl. Trypsin treatment prevented appearance of this surface pattern. Furthermore, no such patterns appeared in media which were made hyperosmotic by the addition of sucrose or sodium glutamate.
Cell Mol Neurobiol 1983 Jun
PMID:Osmotic properties of the squid giant axon and their modifications. 631 79

Crystals for Fab fragments from a monoclonal antibody to HPr of the phosphoenopyruvate:sugar phosphotransferase system of Escherichia coli have been obtained from 14% polyethylene glycol 6000, 5 mM-Tris X HCl, 50 mM-sodium phosphate and 0.2 M-sodium chloride at pH 8.0. The space group is P2(1) with a = 110.85 A, b = 66.18 A, c = 67.21 A, beta = 113.0 degrees and Z = 4. The crystals exhibit the forms [100], [011] and [011] and the solvent content is 47%.
J Mol Biol 1984 Aug 05
PMID:Preliminary crystallographic data for a monoclonal Fab fragment specific for HPr of the phosphoenolpyruvate: sugar phosphotransferase system of Escherichia coli. 637 99

During or immediately after transcription of chromatin the high molecular weight pre-mRNA is complexes with proteins and low molecular weight RNA (lmwRNA). In the presence of a cytosolic RNase inhibitor pre-mRNA-protein complexes, designated as polyparticles, can be isolated from rat liver nuclei. The polyparticles are characterized by a maximum of their sedimentation coefficient of around 90 S, a protein to RNA ratio of 4.1, and a density in CsCl of 1.4 g/cm3. A set of 6--10 basic proteins of molecular weights between 30 and 45 kd as well as a multitude of polypeptides of higher molecular weights is associated with the rapidly labeled, polydisperse, high molecular weight RNA and several lmwRNA species. In order to study the structure of these very complex nuclear RNP complexes, the polyparticles were incubated at various concentrations of sodium chloride, urea or proteinases of different specificities (trypsin, chymotrypsin, proteinase K), recentrifuged through a sucrose layer and analyzed with respect to their sedimentation behavior, their protein to RNA ratios and their protein- and RNA components. Rhe results of these experiments led us to the proposal of a structural model which is presented here.
Mol Biol Rep 1981 May 22
PMID:The structure of ribonucleoprotein particles from rat liver nuclei. 701 68

Mutations in ribosomal protein L6 cause (i) loss of viability of cells at 0 degrees C, which can be prevented by the presence of sodium chloride or 20% sucrose in the medium, (ii) influx of compounds at low temperature that normally cannot penetrate, and (iii) a defective assembly and maturation of 30S and 50S subunits at low temperature. It is proposed that abnormal interaction of immature subunits (or mutant 70S ribosomes) with the cytoplasmic membrane is responsible for triggering breakdown of membrane stability during cold shock.
Mol Gen Genet 1981
PMID:Ribosomal mutation in Escherichia coli affecting membrane stability. 702 77


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