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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phosphatidylserine (PtdSer) potentiates histamine secretion from mast cells exposed to concanavalin A and Ca2+. In order to identify the form of PtdSer that is responsible for its effect on mast cell secretion, PtdSer containing a tritium-labeled serine moiety (3H-PtdSer) was synthesized from egg yolk phosphatidylcholine. The critical micelle concentration (CMC) of 3H-PtdSer and the binding isotherm for 3H-PtdSer interaction with mast cells were determined. The midpoints of the binding isotherm and the dose-response curve for potentiation of secretion coincide and are 2 orders of magnitude greater than the CMC. The shape of the binding curve is explicable either in terms of simple binding of preformed PtdSer micelles or of cooperative binding of monomeric PtdSer in which the number of molecules cooperatively associating with a mast cell binding site is equal to the number of monomers in a PtdSer micelle. In either case, at equilibrium, PtdSer micelles are bound to the mast cells. The number of PtdSer molecules bound to a single mast cell at equilibrium was estimated to be 3.7 X 10(9).
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PMID:Interaction of phosphatidylserine with mast cells. 8 84

The IgE-mediated, antigen-induced release of histamine from human lung tissue causes profound changes in lung cyclic adenosine monophosphate and cyclic guanosine monophosphate. Exogenous histamine similarly induces increases in both cyclic nucleotides; pretreatment with H-1 antihistamines prevents the increase in cyclic guanosine monophosphate, whereas H-2 antihistamines prevent the increase in cyclic adenosine monophosphate. Anaphylaxis of human lung in vitro is unaffected by the presence of 1-100 micron histamine, H-1 antihistamines, H-2 antihistamines, or combinations of these agents despite the production of selective increases in total lung cyclic nucleotides. Futhermore, selective histamine agonists (2-methylhistamine [H-1 agonist] or dimaprit [H-2 agonist]) also fail to significantly influence the immunologic release of mediators. Histamine examined in the presence of ethylenediaminetetra-acetate was no more capable of modulating mediator release than when in the presence of calcium, in contrast to previous studies involving the human basophilic leukocyte. Therefore, the human lung mast cell is unresponsive to histamine with regard to modulating the antigen-induced, IgE-dependent, generation of mediators.
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PMID:Human lung tissue and anaphylaxis: the effects of histamine on the immunologic release of mediators. 8 41

Cyclic somatostatin strongly stimulated secretion of histamine from rat peritoneal mast cells. The energy, temperature and calcium dependence of this effect indicate that the action of somatostatin on the mast cells is similar to that of the classic mast cell secretagogue compound 48/80 and is to induce exocytosis.
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PMID:Somatostatin induces histamine secretion from rat peritoneal mast cells. 8 50

The structural basis for the highly specific action of phosphatidylserine in enhancing mast cell histamine secretion induced by concanavalin A was investigated by studying the activities of three N-substituted derivatives: N-acetyl phosphatidylserine, N-1-dimethylaminonaphthalene-5-sulfonly phosphatidylserine, and N-4-nitrobenzo-2-oxa-1,3-diazole phosphatidylserine. None of the derivatives was capable of activating concanavalin A-induced histamine secretion at concentrations two to three times that required for maximal activation by phosphatidylserine. Instead, the derivatives were found to inhibit the secretory response of mast cells to the calcium ionophore A23187 as well as to concanavalin A. The inhibition was noncytotoxic, partially reversible by washing, and associated with binding of N-substituted phosphatidylserine to the mast cell.
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PMID:Inhibition of mast cell histamine secretion by N-substituteed derivatives of phosphatidylserine. 8 10

Thapsigargin (Tg) is a pure chemical compound isolated from Thapsia garganica with a molecular weight of 650. It releases histamine from isolated rat mast cells but not from isolated histamine-retaining mast cell granules. The rate of release is markedly influenced by pretreatment of mast cells with Tg prior to the addition of calcium. In agreement with the effect of the ionophore A23187 but in contrast to many other calcium-dependent histamine-releasing agents, cells preincubated with Tg respond to the secretory action of calcium whenever the ion is introduced. However, after dilution of Tg-pretreated cells histamine release induced by the addition of calcium became dependent on the time of its addition. The secretory reaction induced by Tg and calcium can be divided into a two-step reaction at 37 degrees C. Pretreatment of mass cells with Tg renders the cells insensitive to the secretory action of compound 48/80 in the absence of calcium, and this effect could be partly counteracted if 1 mM of strontium was added together with compound 48/80. It is concluded that among various calcium- and energy-dependent histamine-releasing agents Tg most closely resembles the action of fluoride on isolated rat mast cells.
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PMID:On the mechanism of histamine release induced by thapsigargin from Thapsia garganica L. 8 85

The activation of cellular function following the direct introduction of Ca2+ into the cytosol by the use of a Ca2+-transporting ionophore has served to confirm the widely held idea that Ca2+ has the status of a second messenger in many cell types. However, this evidence has been obtained largely from the use of a single ionophore, the antibiotic A23187; experiments with X537A, which is another ionophorous antibiotic capable of transporting Ca2+ (ref. 3), have failed to show the expected characteristics. For example, histamine release from rat mast cells mediated by X537A is neither dependent on extracellular Ca2+ nor prevented by metabolic inhibitors. Ionomycin is a recently described polyether antibiotic produced by Streptomyces conglobatus ATCC 31005, and is active against Gram-positive bacteria. The antibiotic action is presumably due to its ionophorous properties, as it extracts Ca2+ from an aqueous phase into an organic phase with a stoichiometry of 1:1 (ref. 6). The ionophore is also capable of transporting 45Ca2+ across biological membranes (our unpublished results). Here we report the application of ionomycin to rat mast cells. We show that ionomycin stimulates mast cell secretion solely through its ability to form a lipid-soluble calcium complex, and thus to convey Ca2+ across the hydrocarbon region of the cell membrane.
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PMID:Ionomycin stimulates mast cell histamine secretion by forming a lipid-soluble calcium complex. 9 64

We have used the mast cell as a model system for studying some of the membrane events which occur during exocytosis. Our observations indicate that the maximum cluster size of IgE molecules necessary for the 'on' signal to activate a mast cell is ten or less, and that the 'off' signal is not associated with the gross patching or pinocytosis of IgE and its Fc receptors. Furthermore, the use of Con A-Sepharose beads to stimulate mast cells has shown that such signalling is localized to the areas of stimulus, but this localization is not a function of desensitization over the rest of the cell since the subsequent addition of soluble Con A to locally released cells induced generalized degranulation. Ca2+ influx therefore acts in a localized manner to initiate degranulation. Following receptor cross-linking, most of the membrane proteins and the layer of intervening cytoplasm are laterally displaced away from the areas of membrane interaction. This displacement may act as the signal for fusion to occur. The resulting fused bilayers are predominantly lipid, a situation which may be common in all transient membrane fusion.
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PMID:Some membrane events occurring during fusion and exocytosis in rat peritoneal mast cells. 9 11

1. The concentration dependence on ATP of mast cell histamine secretion in the presence of various concentrations of Mg2+ and Ca2+ confirms that the agonist form of ATP is the free form of ATP (ATP(free) not bound to divalent cations, i.e. ATP4-. It induces 50% activation at about 1.2 microM, maximal secretion at about 2.7 microM and 50% self-inhibition at about 4.4 microM. 2. The divalent cations Mg2+ and Ca2+ were used to buffer ATP(tree) in the range 1-8 microM in the presence of much higher concentrations of ATP(total). In addition to its effect as a buffer for ATP, Ca2+ is required for secretion. 3. With ATP(free) at 1 microM, the time-course of histamine secretion is characterized by a delay of about 10 min before secretion commences. With increasing concentration of ATP(free) the delay becomes shorter (less than 5 min with ATP(free) at 2 microM). 4. Secretion commences promptly on addition of Ca2+ to cells which have been pretreated with low concentrations of ATP(free) (less than 2 microM). This observation suggests that the delay normally observed represents the time taken for Ca2+ sensitivity to develop (i.e. probably the time taken for Ca2+ channels to open). 5. Late addition of Ca2+ to cells pretreated with higher concentrations of ATP(free) (greater than 2 microM) results in a reduced amount of histamine secretion compared with that which normally occurs. This reduction (which increases with time of exposure to ATP) and the self-inhibition due to higher concentrations of ATP(free) may be two facets of a common inhibitory mechanism. 6. These results are discussed in the light of other experiments which show that mast cells treated with ATP(free) at self-inhibitory concentrations become permeable to phosphorylated metabolites and nucleotides.
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PMID:Activation and inhibition of calcium-dependent histamine secretion by ATP ions applied to rat mast cells. 9 38

The Streptomyces aureofaciens extracellular proteolytic system was split into four fractions by carboxymethylcellulose (CMC) column chromatography giving three purely caseinolytic fractions and one fraction active toward both starch and casein. The first caseinolytic and amylolytic fraction was further fractionated by DEAE-Sephadex A-50 chromatography into one purely amylolytic fraction and another showing both activities, was refractioned into four new fractions by DEAE-cellulose chromatography. These fractions were found to be heterogeneous by polyacrylamide gel electrophoresis, three of them acted on both starch and casein and a fourth was only caseinolytic. The second CMC fraction was further purified by CMC rechromatography to an homogeneous fraction that hydrolyzes carboxypeptidase A(EC 3.4.2.1) synthetic substrates and solubilizes elastin. It had only one polypeptide chain with a molecular weight of about 28000 daltons, a high thermal stability in the presence of calcium ions, a pH optimum of about 6.8, and a maximal caseinolytic activity at about 50 degrees C.
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PMID:Fractionation of the proteolytic and amylolytic complex enzyme system of streptomyces aureofaciens and some properties of fractions. 10 83

Angiotensin-converting enzyme has been solubilized from a particulate fraction of rabbit lung and purified to apparent homogeneity in 11% yield by a procedure including fractionation with DEAE-cellulose and calcium phosphate gel, elution from Sephadex G-200, and lectin affinity chromatography. The molecular weight estimated by equilibrium sedimentation was approximately 129,000, either in the absence or presence of 6 M guanidine hydrochloride. A slightly higher value of 140,000 determined for the reduced, denatured protein by gel electrophoresis in the presence of sodium dodecyl sulfate and a much higher figure derived from gel filtration are probably due to the glycoprotein nature of the enzyme. Its oligosaccharide content accounted for 26% of the weight calculated from its amino acid and carbohydrate composition. The estimated content of sugar residues per mole was: galactose, 57; N-acetylglucosamine, 53; mannose, 43; N-acetylneuraminic acid, 19; and fucose, 4. Threonine and alanine were identified, respectively, as NH2-terminal and COOH-terminal residues by the dansylation procedure and by digestion with carboxypeptidase A. The enzyme was found to contain approximately 1 g atom of zinc per mol. Km values for hydrolysis of hippurylhistidylleucine and angiotensin I were 2.3 and 0.07 mM, and the corresponding turnover numbers were 15,430 and 792 mol/min/mol at 37 degrees. Bradykinin was also a substrate, and release of its COOH-terminal dipeptide, Phe-Arg, was catalyzed at a comparable rate to that of His-Leu from the COOH terminus of angiotensin I. Enzyme activity required the presence of chloride ions and was inhibited by EDTA and by low concentrations of Bothrops bradykinin-potentiating peptides. In addition, hydrolysis of hippurylhistidylleucine was inhibited competitively by other defined peptides, including di- and tripeptides, which were not substrates.
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PMID:Pulmonary angiotensin-converting enzyme. Structural and catalytic properties. 16 57


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