Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. D-Galactose dehydrogenase from Pseudomonas saccharophila (molecular weight 102 000) dissociates in 8 M urea into its subunits (molecular weight 25 000) which migrate in polyacrylamide gels, containing 8 M urea, as a single band. 2. The N-terminal residue determination by the dansyl method revealed only serine. 3. The C-terminal group determination with carboxypeptidase A and B indicated the sequence -Tyr-His-Leu. Leucine as the single C-terminal amino acid was confirmed by the tritiation method and by tritiation and subsequent degradation with carboxypeptidases. 4. The fragmentation of D-galactose dehydrogenase (24 mol methionine per mol enzyme) by CNBr resulted in six peptides, as detected in disc electrophoresis and substantiated by end group determination, indicating the identity of the subunits. 5. The treatment of D-galactose dehydrogenase (24 mol lysine and 52 mol arginine per mol enzyme) with trypsin and subsequent peptide mapping showed 21, perhaps 22 peptides, indicating a structure comprising four identical subunits.
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PMID:Subunit structure of D-galactose dehydrogenase from Pseudomonas saccharophila. 113 86

Although optical resolution of alpha-methylphenylalanine (alpha-Me-Phe) has been achieved by the action of carboxypeptidase A on the N-trifluoroacetyl derivative of the amino acid (TFA-alpha-Me-Phe), it is improbable that an alpha-methyl substrate could bind in the same orientation as glycyl-L-tyrosine, due to steric interaction of the alpha-methyl group with an atom in the imidazole ring of zinc ligand His-196. The kinetic parameters for TFA-alpha-Me-Phe and for an ester substrate bearing an alpha-methyl group (beta-hippuryl-alpha-methylphenyllactic acid, HMPL) have been determined and compared to those for the appropriate nonmethylated control substrates. Both TFA-alpha-Me-Phe and HMPL appear to be bound nearly as well as are their respective controls, and HMPL is hydrolyzed nearly as rapidly as its control. TFA-alpha-Me-Phe, however, is hydrolyzed only about one-fiftieth as rapidly as is the nonmethylated substrate. These findings are consistent with the possibilities that: (1) the proposed substrate-induced conformational shift of Tyr-248 is hindered when the methylated substrates are bound; (2) the orientation in which alpha-methyl substrates are bound precludes optimal positioning of Tyr-248 and the scissile bond even after the rotation of Tyr-248 has occurred; (3) amides and esters are bound in different orientations, and in the amide orientation an alpha-methyl group is so directed as to interfere with the approach of Glu-270 to the scissile bond.
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PMID:alpha-Methyl substrates of carboxypeptidase A. A steric probe of the active site. 114 72

The complete covalent structure of a small, basic protein with cardiotoxic activity is described. This has been isolated from the venom of Naja nigricollis by gel filtration on Sephadex G-75 and gradient ion exchange chromatography on Bio-Rex 70. The cardiotoxin, molecular weight 6806 from amino acid composition, consists of 60 amino acids, cross-linked by four disulfide bridges, connecting 3-21, 14-38, 42-53, and 54-59. The protein contains one residue of tryptophan, phenylalanine, and glutamic acid, two residues of arginine and tyrosine, four residues of methionine, and nine residues of lysine. Histidine is absent. The chymotryptic peptides of the oxidized and S-carboxymethylated protein were isolated by gel filtration on Sephadex G-25 and zone electrophoresis on a cellulose column. The sequence was determined by Edman degradation, using the (manual) direct phenylthiohydantoin method and with the use of carboxypeptidase A. Disulfide pairing was determined on thermolysin cleaved peptides from the native protein. The sequence is shown to be homologous to other cardiotoxins and a lytic factor from snake venoms and also shows homology, both in sequence and disulfide pairing to neurotoxins. A partial reduction experiment in the absence of denaturing agent using 14-C-labeled iodoacetic acid as S-carboxymethylating agent shows that disulfide bonds 14-38 and 42-53 were reduced fastest followed marginally by 54-59, and then bond 3-21.
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PMID:The complete covalent structure of a cardiotoxin from the venom of Naja nigricollis (African black-necked spitting cobra). 114 81

Axon reflex vasodilation following injury to the skin of the pinna of the ear was studied in rats by a thermometric method. Post-traumatic vaso-dilatation did not occur in animals treated with tyrosine ethyl ester, an inhibitor of chymotrypsin. Vasodilatation was not affected by treatment of the rats with chlorpheniramine (antihistamine) or cyproheptadine (antihistamine and anti-serotinin) or with aprotinin, soybean trypsin inhibitor, epsilon-aminocaproic acid or tosyl arginine methyl ester (inhibitors of trypsin and of some other proteinases). Taken in conjunction with the results of other investigations, these findings indicate that in the skin of the rat: (a) histamine and serotinin are not essential for the initiation of axon reflexes, and (b) the chymotrypsin-like proteinase of mast cell granules, released as the result of antidromic activity in sensory axons, may act as a kininogenase and be responsible for causing dilatation of arterioles at the efferent limb of the axon reflex.
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PMID:Evidence for the involvement of vasoactive constitutents of mast cells in axon reflex vasodilatation in the skin of the rat. 125 6

Inhibitors of the peptidase and esterase activities of carboxypeptidases A and B have been isolated from extracts of Ascaris lumbricoides var suis. These proteins were obtained by treatment of the aqueous extracts at low pH, precipitation with ammonium sulfate, molecular sieving on Bio-Gel P-4, and chromatography on DEAE-cellulose. The inhibitors were resolved into three homogeneous peaks on CM-cellulose. These components, CM-A, CM-B, and CM-C, have constant specific activity and were recovered in a 41% yield. They moved as single bands when subjected to electrophoresis at high or low pH on polyacrylamide gels and they have similar amino acid compositions. Methionine, tyrosine, and cysteine are absent from each of the inhibitors. The 65 residues of CM-B suggest a minimum molecular weight of 7530, in close agreement to the value of 7600 +/- 200 determined on a Bio-Gel P-100 column. Each of the proteins has the same NH2-terminal residues, NH2-Asx-Glx-Val-Glx- and the same COOH-terminal residue, leucine. A plot of per cent acrylamide versus log relative mobility suggests that the three proteins are charge isomers. CM-B appears to be stable to high NaCl concentrations, extremes of pH, high temperatures, and digestion by intestinal proteases. Carboxypeptidase C, carboxypeptidase N, and yeast protease C are not inhibited by CM-B. However, the exopeptidase and esterase activities of human carboxypeptidase A are inhibited. The inhibitors appear to bind to bovine carboxypeptidase A with an atypical stoichiometry. Two moles of CM-B inhibitor bind to 1 mol of enzyme. The evidence is: (a) a demonstrated purity of bovine carboxypeptidase A, (b) minimal and maximal inhibitor molecular weights by different methods, of 7600 and 8300, and (c) a maximum specific activity of apparently homogeneous inhibitors which is 50% of that predicted for unit stoichiometry.
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PMID:Characterization of proteins from Ascaris lumbricoides which bind specifically to carboxypeptidase. 126 22

Recent evidence suggests that tyrosine kinases play an important role in signal transduction mechanisms utilized by a range of different agonists in many cell types. We have investigated the effects of four different inhibitors of tyrosine kinases on IgE-dependent histamine release from human lung mast cells and basophils. Genistein inhibited the anti-IgE-induced histamine release from human basophils (at 10 microM genistein, inhibition = 55 +/- 5%, n = 17, P < 0.005) with an IC50 of 8 microM, but was much less effective in the human lung mast cell (at 10 microM, inhibition = 18 +/- 6%, n = 11, P < 0.05). Two inactive analogs of genistein, genistin and diadzein, failed to affect anti-IgE-induced histamine release significantly in either mast cells or basophils. A second inhibitor of tyrosine kinases, tyrphostin 25, inhibited IgE-dependent release from basophils (at 10 microM, inhibition = 25 +/- 7%, n = 6, P < 0.05) though it was less effective than genistein and failed to affect IgE-induced histamine release from human lung mast cells (at 10 microM, inhibition = 22 +/- 16%, n = 5, P = NS). In contrast, methyl 2,5 dihydroxycinnamate (MDC) failed to inhibit anti-IgE-dependent histamine release in human basophils (at 10 microM, inhibition = 3 +/- 3%, n = 5, P = NS) but proved to be an effective inhibitor of anti-IgE-induced degranulation in human lung mast cells (at 10 microM, inhibition = 53 +/- 16%, n = 5, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Role of tyrosine kinases in IgE-mediated signal transduction in human lung mast cells and basophils. 128 Apr 50

The active site of angiotensin-converting enzyme (ACE) has been shown by chemical modification to contain a critical tyrosine residue, identified as Tyr-200 in human testis ACE (hTACE). We have expressed a mutant hTACE containing a Tyr-200 to Phe mutation. The mutant exhibits a marked decrease in kcat: 15-fold and 7-fold for the hydrolysis of furanacryloyl-Phe-Gly-Gly and angiotensin I, respectively, whereas its Km increases by only 1.6- and 2.2-fold, respectively. We conclude that Tyr-200 is not required for substrate binding. Instead, the effect on kcat together with a 100-fold decrease in affinity for the ACE inhibitor lisinopril indicates that Tyr-200 may participate in catalysis by stabilizing the transition state complex. Thus, Tyr-200 in hTACE has a role analogous to that of Tyr-198 in carboxypeptidase A.
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PMID:The functional role of tyrosine-200 in human testis angiotensin-converting enzyme. 131 88

Mutant mice of mi/mi genotype are osteopetrotic and deficient in tissue mast cells due to a defect in osteoclasts and mast cells. In an effort to further understand the mechanisms behind why mi/mi mouse-derived cultured mast cells (mi/mi-CMC) responded to interleukin-3 (IL-3), but not to the proliferative stimuli presented by fibroblasts, mi/mi-CMC and congenic normal (+/+) mouse-derived CMC (+/+-CMC), both of which expressed the phenotypic characteristics of immature mast cells, were cocultured with Swiss albino/3T3 fibroblasts in a medium containing IL-3. In the in vitro CMC/fibroblast coculture, mi/mi-CMC did not acquire the phenotypes of connective tissue-type mast cells (CTMC), while +/+-CMC did. In addition, attachment of mi/mi-CMC to the fibroblasts was found to be significantly lower than that of +/+-CMC. Because the interaction of c-kit product with its ligand (stem cell factor [SCF]) is known to play an important role not only in proliferation and differentiation of mast cells but also in attachment of CMC to fibroblasts, the expression and function of c-kit were investigated in mi/mi-CMC and +/+-CMC. Recombinant rat SCF (rrSCF164) induced a dose-dependent proliferation of +/+-CMC. Also, rrSCF164 induced +/+-CMC to acquire the phenotypes of CTMC in the medium containing IL-3. By contrast, rrSCF164 did not stimulate the proliferation of mi/mi-CMC nor induce a phenotypic change of the cells from immature mast cells to mature, CTMC-like mast cells. Immunoblotting with antiphosphotyrosine antibody showed that rrSCF164 induced considerable tyrosine phosphorylation of 145- to 165-Kd protein, the product of c-kit, in +/+-CMC, whereas tyrosine phosphorylation of the protein was barely detectable in mi/mi-CMC. Northern blot and flow cytometry analyses showed that mi/mi-CMC expressed much less c-kit at both protein and message levels than +/+-CMC. Further, mi/mi-CMC were found to differ from +/+-CMC in the expression of mouse mast cell protease-6 (MMCP-6) and MMCP-2 messenger RNA transcripts. These results suggest that the gene product of the mi locus may be important in regulating the expression of gene products such as c-kit, and that mast cell deficiency of mi/mi mice appears to be due, at least in part, to impaired signaling through the c-kit receptor because of the low c-kit expression.
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PMID:Low c-kit expression of cultured mast cells of mi/mi genotype may be involved in their defective responses to fibroblasts that express the ligand for c-kit. 138 28

The high affinity receptor for IgE (Fc epsilon RI) is present on mast cells and basophils, and the aggregation of IgE-occupied receptors by Ag is responsible for the release of allergic mediators. The Fc epsilon RI is composed of at least three different subunits, alpha, beta, and gamma, with the alpha subunit binding IgE. The series of biochemical events linking receptor aggregation to the release of mediators has not been fully delineated. As a step towards understanding these processes, and for the development of functional cell lines, we have transfected the human Fc epsilon RI alpha subunit into the rat mast cell line RBL 2H3. These human Fc epsilon RI alpha-transfected cell lines have been characterized with respect to the association of the human alpha subunit with endogenous rat beta and gamma subunits and the ability of aggregated Fc epsilon RI alpha subunits to mediate a variety of biochemical events. The signal transduction events monitored include phosphoinositide hydrolysis, Ca2+ mobilization, tyrosine phosphorylation, histamine release, and arachidonic acid metabolism. In all cases, the events mediated by aggregating human Fc epsilon RI alpha subunits were indistinguishable from those produced via the rat Fc epsilon RI alpha. These results demonstrate that the human Fc epsilon RI alpha subunit can functionally substitute for the rat Fc epsilon RI alpha subunit during signal transduction. The availability of this cell line will provide a means of evaluating potential Fc epsilon RI antagonists.
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PMID:Conservation of signal transduction mechanisms via the human Fc epsilon RI alpha after transfection into a rat mast cell line, RBL 2H3. 138 4

We have isolated and characterized subpopulations of the rat mucosal mast cell line, RBL-2H3, carrying either high or low density of a glycoprotein, recently established as mast cell function-associated antigen (MAFA, Ortega et al., 1991), on their surface. These populations were investigated in order to better define the involvement of the MAFA in coupling the immunological stimulation of mast cells to mediator release. The MAFA density on the cell surface of the deficient subpopulation was less than or equal to 10-20% that of the parental population and this phenotype was found to be stably maintained for several months. In contrast, the MAFA-enriched cells had maximally twice the number of copies per cell surface than that of the parental population and this phenotype was less stable. Significantly, low copy number of MAFA on the cell's surface was accompanied by a markedly different secretory response, i.e. (i) a considerable decrease in the secretory response to the Fc epsilon RI-mediated stimulus (ii) a marked enhancement of the ionomycin induced secretion. In order to gain insight into the causes for this decrease in cellular response to the Fc epsilon RI-mediated stimulus, we measured the amplitudes of several biochemical processes which are assigned to the stimulus-secretion coupling cascade. The Fc epsilon RI-mediated uptake of 45Ca2+ by the MAFA-deficient cells was considerably lower than that of the parental and MAFA-enriched cells. Similarly, these cell's Fc epsilon RI-induced rise in [Ca2+]i (both the initial transient as well as the sustained elevation), was markedly lower than that of the parental line and the MAFA-enriched cells. Moreover, the low initial transient rise in [Ca2+]i was found to be correlated with the decrease in Fc epsilon RI-mediated IP3 levels. We therefore examined the cell's content of the phosphatidyl-inositides hydrolyzing enzyme, phospholipase C gamma 1. This was found to be similar in the parental line and in its derived subpopulations. However, PLC gamma 1 activation, as measured by the time course of phosphorylation of its tyrosines, showed a marked difference: while PLC gamma 1 tyrosine phosphorylation, in the parental cells, was only transient (detected already 1 min after antigen addition and declined afterwards to basal levels at ca. 10 min), in the MAFA-deficient cells, tyrosine phosphorylated PLC gamma 1 was also observed 1 min after antigen addition, yet showed no decrease with time in its phosphorylation intensity for up to 30 min.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Variants of the mucosal mast cell line (RBL-2H3) deficient in a functional membrane glycoprotein. 145 97


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