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Query: UNIPROT:P06889 (Mol)
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Erythrocytes from various species have been partitioned in aqueous two-phase systems consisting of water, dextran, poly-(ethylene glycol), salt and buffer. The terminal hydroxyl groups of the latter polymer were esterified with palmitic, oleic, linoleic and linolenic acids, as well as with deoxycholic acid. In a two-phase system containing unesterified poly(ethylene glycol) the erythrocytes are exclusively in the dextran-rich lower phase. When the poly(ethylene glycol)-rich upper phase depending on the type and concentration of esterified acid. Palmitate ester is most effective in increasing the affinity of the cells for the upper phase, followed by oleate, linolate, linolenate, and deoxycholate esters. The partition behaviour of erythrocytes from various species differs considerably. Two groups can be distinguished: one consisting of erythrocytes from dog, guinea pig and rat, the other from human, sheep and rabbit. This division can be correlated to the content of sphingomyelin and phosphatidyl choline in the erythrocyte membranes.
Mol Cell Biochem 1976 Feb 16
PMID:Hydrophobic surface properties of erythrocytes studied by affinity partition in aqueous two-phase systems. 125 48

Antibodies to DNA can be found in the circulation of the majority of patients with Systemic Lupus Erythematosus (SLE). They are quite specific for this disease, which makes their detection an important diagnostic aid to the clinician. Fluctuations in the level of anti-dsDNA in an individual patient generally parallel the clinical state of that patient. Furthermore, the presence of anti-dsDNA may precede the diagnosis of SLE by more than a year. Four methods relevant for the measurement of anti-dsDNA antibodies are discussed in this paper: the ELISA, the indirect immunofluorescence test on Crithidia luciliae, the PEG assay, and the Farr assay. Each of these methods detects a part of the spectrum of anti-dsDNA antibodies present in the circulation of an individual patient. The ELISA is the most sensitive method, whereas the Farr assay is the most specific for SLE. However, with the latter method only antibodies of a relative high avidity for DNA are detected. Mild forms of SLE, where patients only have anti-dsDNA of a low avidity in their circulation, may easily be missed by this technique. Clinically, high avidity anti-dsDNA is related with the more frequent occurrence of nephritis, whereas low avidity anti-dsDNA antibodies are more often found in patients with central nervous system involvement.
Mol Biol Rep 1992 Nov
PMID:Detection of antibodies to DNA: a technical assessment. 128 79

The mechanism of adenylyl cyclase desensitization by carbachol, an agent that stimulates polyphosphoinositide hydrolysis, was studied in thyroid cells. Incubation of cultured dog thyroid cells with 10 microM carbachol for 2-4 hr reduced the subsequent thyrotropic hormone (TSH) stimulation of adenylyl cyclase activity of membrane preparations by approximately 40%. This inhibition was reversed by atropine, occurred even in a Ca(2+)-free medium containing ethylene glycol bis(beta-aminoethylether)-N,N,N',N'-tetraacetic acid, and was not reproduced by the Ca2+ ionophore A23187. The carbachol effect was not prevented by simultaneous incubation of cells with either isobutylmethylxanthine, an inhibitor of phosphodiesterase, or H-7, an inhibitor of protein kinase. Pretreatment of cells with pertussis toxin to inactivate the Gi inhibitory protein also failed to affect the carbachol inhibition. Although carbachol did not reduce the basal or the TSH-stimulated cyclase activities when added to membranes directly during the assay, exposure of cells to carbachol for 2-4 hr resulted in long lasting inhibition of TSH-stimulated cyclase activity (for at least 24 hr); recovery was seen by 48 hr after its removal. Carbachol pretreatment had no effect on 125I-TSH binding to membranes but reduced the cyclase stimulation by not only TSH but also cholera toxin, guanosine 5'-O-(3-thio)triphosphate, and forskolin; it also significantly reduced the cholera toxin-mediated AD[32P]-ribosylation of Gs in membranes. These data indicate that carbachol-induced inhibition of adenylyl cyclase occurs beyond the level of TSH receptor binding and that Gs is a possible site of its action. Thus, in dog thyroid cells, carbachol, via muscarinic receptors, can reduce the adenylyl cyclase activity by a process that does not involve Ca2+ or activation of phosphodiesterase.
Mol Pharmacol 1992 Jan
PMID:Carbachol-induced decrease in thyroid cell adenylyl cyclase activity is independent of calcium and phosphodiesterase activation. 131 Jan 40

DDT1-MF2 smooth muscle cells demonstrated a robust phospholipase C response to norepinephrine, as detected by inositol phosphate accumulation. A selective A1-adenosine receptor agonist, cyclopentyladenosine, caused only a minor stimulation of phospholipase C, which was eliminated in the absence of added extracellular calcium. The simultaneous addition of norepinephrine and cyclopentyladenosine resulted in a synergistic increase in phosphoinositide hydrolysis either in the absence or in the presence of external calcium. In the presence of external calcium and a calcium ionophore, and adenosine agonist caused a significant stimulation of phosphoinositide hydrolysis without the addition of norepinephrine. Influx of extracellular calcium through voltage-sensitive calcium channels did not appear to be required to observe an effect of cyclopentyladenosine, because neither calcium channel antagonists (nifedipine, verapamil, and LaCl3) nor a chelator of extracellular calcium (ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid) were able to alter the degree of potentiation of norepinephrine-stimulated phosphoinositide hydrolysis due to the adenosine agonist. On the other hand, buffering of intracellular calcium concentration with the membrane-permeant calcium chelator quin2 blocked the potentiation. This blockade of potentiation by quin2 was reversed by the addition of extracellular calcium. Agents that stimulated cAMP production or membrane-permeable analogues of cAMP also blocked the action of the adenosine agonist to potentiate norepinephrine-stimulated phosphoinositide hydrolysis. This effect of cAMP was less pronounced in the presence of elevated extracellular calcium and was abolished in the presence of a calcium ionophore. When norepinephrine-stimulated calcium transients were quantitated using fura-2 fluorescence, a reduction in the amplitude of the calcium response was observed in the presence of forskolin. Conversely, both the amplitude and the duration of the calcium response were enhanced by the addition of the adenosine agonist. The results of these studies suggest that the mechanism by which adenosine receptors enhance the stimulation of phosphoinositide hydrolysis is dependent upon a rise in intracellular Ca2+ concentration resulting from the simultaneous activation of alpha 1-adrenergic receptors. The results further suggest that cAMP inhibits this mechanism by decreasing the norepinephrine-stimulated rise in intracellular Ca2+ concentration.
Mol Pharmacol 1992 Mar
PMID:Competitive regulation of phospholipase C responses by cAMP and calcium. 131 17

The paper compares different approaches for the genetic transformation of cauliflower (Agrobacterium-mediated, PEG-mediated and/or electroporation). Transient expression of the neomycin phosphotransferase II (NPTII) gene could be detected after direct gene transfer. Stable transformation was achieved using both Agrobacterium-mediated and direct gene transfer. Expression as well as incorporation of the NPTII sequence could be demonstrated.
Plant Mol Biol 1992 Jun
PMID:Transformation of cauliflower (Brassica oleracea L. var. botrytis)--an experimental survey. 132 Apr 26

The commercially important Indica rice cultivar Oryza sativa cv. IR72 has been transformed using direct gene transfer to protoplasts. PEG-mediated transformation was done with two plasmid constructs containing either a CaMV 35S promoter/HPH chimaeric gene conferring resistance to hygromycin (Hg) or a CaMV 35S promoter/BAR chimaeric gene conferring resistance to a commercial herbicide (Basta) containing phosphinothricin (PPT). We have obtained so far 92 Hgr and 170 PPTr IR72 plants from protoplasts through selection. 31 Hgr and 70 PPTr plants are being grown in the greenhouse to maturity. Data from Southern analysis and enzyme assays proved that the transgene was stably integrated into the host genome and expressed. Transgenic plants showed complete resistance to high doses of the commercial formulations of PPT.
Plant Mol Biol 1992 Nov
PMID:Herbicide-resistant Indica rice plants from IRRI breeding line IR72 after PEG-mediated transformation of protoplasts. 133 95

In vitro Ca++ activates gelsolin to sever F-actin and form a gelsolin-actin (GA) complex at the+end of F-actin that is not dissociated by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) but is separated by EGTA+PIP/PIP2. The gelsolin blocks the+end on the actin filament, but the-end of the filament can still initiate actin polymerization. In thrombin activated platelets, evidence suggests that severing of F-actin by gelsolin increases GA complex, creates one-end actin nucleus and one cryptic+end actin nucleus per cut, and then dissociates to yield free+ends to nucleate rapid actin assembly. We examined the role of F-actin severing in creation and regulation of nuclei and polymerization in polymorphonuclear neutrophils (PMNs). At 2-s intervals after formyl peptide (FMLP) activation of endotoxin free (ETF) PMNs, change in GA complex was correlated with change in+end actin nuclei,-end actin nuclei, and F-actin content. GA complex was quantitated by electrophoretograms of proteins absorbed by antigelsolin from cells lysed in 10 mM EGTA,+end actin nuclei as cytochalasin (CD) sensitive and-end actin nuclei as CD insensitive increases in G-pyrenyl actin polymerization rates induced by the same PMNs, and F-actin content by NBDphallacidin binding to fixed cells. Thirty three percent of gelsolin was in GA complex in basal ETF PMNs; from 2-6 s, GA complexes dissociate (low = 15% at 10 s) and sequentially+end nuclei and F-actin content and then-end nuclei increase to a maximum at 10 s. At > s GA complex increase toward basal and + end nuclei and F-actin content returned toward basal. These kinetic data show gelsolin regulates availability of + end nuclei and actin polymerization in FMLP. However, absence of an initial increase in GA complex or - end nucleating activity shows FMLP activation does not cause gelsolin to sever F- or to bind G-actin to create cryptic + end nuclei in PMNs; the results suggest the + nucleus formation is gelsolin independent.
Mol Biol Cell 1992 Dec
PMID:Role of gelsolin interaction with actin in regulation and creation of actin nuclei in chemotactic peptide activated polymorphonuclear neutrophils. 133 90

The endogenous neurotransmitter candidates L-aspartate, L-cysteine sulfinate (CSA), L-glutamate, L-homocysteate (HCA), and the endogenously occurring analogue quinolinate were compared in terms of potency, maximal activity, and selectivity for steady state activation of N-methyl-D-aspartate (NMDA) and non-NMDA [(RS)-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)] types of glutamate receptors expressed in Xenopus oocytes injected with mRNA isolated from rat brain (minus cerebellum). Selective activation of NMDA receptors was achieved by deleting Mg2+ and including 3-10 microM glycine in the perfusion medium and by applying ligands in the presence of 30 microM quisqualate, which blocks the AMPA receptor and desensitizes the oocyte's own Ca(2+)-dependent Cl- current. Oocytes were voltage clamped, and steady state inward currents were measured in response to perfusion with agonists at known concentrations. Under the NMDA receptor-preferring condition, the potency rank order was L-glutamate (EC50 = 2.2 microM, 95% confidence interval = 1.4-3.6 microM) greater than L-aspartate (13 microM) = HCA (13 microM) greater than CSA (59 microM) greater than quinolinate (greater than or equal to 7200 microM). All amino acids tested evoked similar maximal currents, which were 120-159% that of NMDA itself. The Hill coefficient was greater than 1 for all agonists except L-HCA (0.6), which might reflect heterogeneity of NMDA receptors expressed. This was supported by the finding that glycine was more potent in combination with HCA than NMDA, in activating NMDA receptors. To study the activity of agonists at AMPA receptors, glycine and quisqualate were omitted and 1 mM Mg2+ was included to block NMDA receptors. Ca(2+)-dependent Cl- currents activated by L-glutamate were prevented by inclusion of 0.4 M ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid in the recording electrode. All amino acids were less potent at AMPA receptors than at NMDA receptors; the potency rank order for steady state activation of AMPA receptors was L-glutamate (EC50 = 11 microM, 95% confidence interval = 7.3-18 microM) greater than HCA (430 microM) greater than CSA (3300 microM). L-Aspartate and quinolinate produced little or no inward current even up to 10 mM, i.e., were inactive at forebrain AMPA receptors. The maximal currents activated by all amino acids at steady state were 5-10% that of kainate, presumably due to severe desensitization of the AMPA receptor by the natural agonists. These results are consistent with L-glutamate acting as a mixed agonist at both AMPA and NMDA synaptic receptors and L-aspartate being involved exclusively in NMDA receptor-mediated synapses.
Mol Pharmacol 1992 Mar
PMID:Selectivity of amino acid transmitters acting at N-methyl-D-aspartate and amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors. 137 86

Fractionation of mouse serum by precipitation with a critical amount of polyethylene glycol 6000 (PEG; 11% w/v) results in a classical and alternative pathway-independent activation of the terminal complement route. The activation can take place after the separation of an activating principle together with the terminal route components from a natural regulator. The isolation and identification of the regulatory component preventing this activation in serum, is subject of this paper. The regulator was purified by fractionated PEG-precipitation (15-25%), followed by heparin-Sepharose affinity, Mono Q anion-exchange, and Superose 12 gel filtration chromatography. The regulator appeared to be a single-chain protein with a Mr of 96 k. A protein with similar activity purified from human serum had a Mr of 104 k and was functionally and antigenically indistinguishable from C1-INH. The mouse 96 k protein inhibited C1-esterase activity indicating that this protein is indeed C1-INH. Mouse C1-INH regulates the PEG fractionation-induced bypass activation of complement, but does not interfere with the assembly or the lytic activity of membrane attack complexes. alpha 2-Macroglobulin appeared also to be capable of inhibiting the PEG-precipitation-induced activation process, but with lower efficiency.
Mol Immunol 1992 Mar
PMID:C1-inhibitor prevents PEG fractionation-induced, EDTA-resistant activation of mouse complement. 137 56

Rusticyanin is a 16.5 kDa type I blue copper protein isolated from Thiobacillus ferrooxidans. This organism can grow on Fe2+ as its sole energy source. Rusticyanin is thought to be a principal component in the iron respiratory electron transport chain of T. ferrooxidans. As a component of the periplasmic space of an acidophilic bacterium, rusticyanin is remarkably stable at acidic pH. It is redox-active down to pH 0.2. Crystals of rusticyanin have been grown from solutions of PEG 8000 by the hanging-drop vapor diffusion method. The crystals are orthorhombic, space group P2(1)2(1)2(1), with unit cell dimensions a = 32.36 A, b = 60.37 A, c = 74.60 A. The crystals diffract to 2.0 A resolution and they are stable in the X-ray beam for at least two days.
J Mol Biol 1992 Sep 20
PMID:Crystallization and preliminary X-ray crystallographic studies of rusticyanin from Thiobacillus ferrooxidans. 140 74


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