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)

Mouse mast cell chymases are granule-associated serine proteinases with chymotrypsin-like substrate specificities. cDNAs for two new chymases were isolated from a cDNA library constructed using mRNA from ABFTL-6 mouse mast cells by screening with a rat mast cell proteinase cDNA. The deduced amino acid sequence of mouse chymase 1 consists of a 226 amino acid catalytic portion and a 21 amino acid preprosequence. Chymase 1 is unusual in that an Asn occurs in the substrate binding pocket, a feature that has not been observed in any other serine proteinase. Also, chymase 1 is expected to have a large positive charge (+13) at physiological pH. A partial cDNA for chymase 2 encodes 177 residues of the carboxy terminal portion of a second proteinase distinct from chymase 1. Chymase 2 cDNA contains a highly conserved intron/exon junction, a high positive charge (+17) and a novel, second potential N-glycosylation site. Transcripts for both chymases are found in ABFTL-6 mast cells, but only chymase 2 mRNA is in mouse connective tissue mast cells. These data suggest that these chymases have distinct enzymatic properties and tissue-specific patterns of gene expression.
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PMID:Molecular cloning and characterization of mouse mast cell chymases. 137 47

Incubation of radiolabeled human C3a with rat peritoneal mast cells resulted in high levels of uptake and extensive degradation of the ligand. Both cell-bound and free radiolabeled human C3a underwent extensive degradation by rat mast cells even at 0 degrees C. We examined several protease inhibitors for their ability to prevent degradation of radiolabeled human C3a by the rat mast cells. The inhibitors PMSF, chymostatin, and soybean trypsin inhibitor were most effective in preventing radiolabeled human C3a degradation. Degradation of the cell-bound ligand was totally inhibited only by PMSF. These compounds are effective inhibitors of a chymotrypsin-like enzyme (chymase) extracted from rat mast cells. Chemical cross-linking of radiolabeled human C3a to surface components on the rat mast cells, in the presence of PMSF, revealed one major and two minor bands. The mast cell component in both the major and minor bands proved to be chymase-associated based on a direct comparison with purified chymase isolated from rat mast cells. However, neither antichymase antibody nor chymase inhibitors influenced the degranulating activity of C3a on rat mast cells that occur independently of the C3a-chymase interactions. We conclude that there are neither specific C3a-binding sites on rat mast cells nor specific receptors whose occupancy leads to cellular activation. Although human C3ades Arg is inactive on guinea pig ileal and lung tissue, it binds to and induces degranulation of rat mast cells, as well as enhances vascular permeability in rat skin, at concentrations nearly identical to that of intact C3a. The fact that both C3a and C3ades Arg stimulated mast cell activation, at concentrations in excess of 10(-6) M, argues against specific binding sites for the anaphylatoxin on rat mast cells. It is proposed that the cationic C3a molecule activates rat mast cells in a secretory and nonlytic manner by a nonspecific mechanism similar to that of other polybasic compounds.
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PMID:Anaphylatoxin binding and degradation by rat peritoneal mast cells. Mechanisms of degranulation and control. 169 12

We have recently identified and characterized a chymotrypsin-like serine proteinase in human heart (human heart chymase) that is the most catalytically efficient enzyme described, thus far, for the cleavage of angiotensin I to yield angiotensin II and the dipeptide His-Leu. Compared to other chymases, this enzyme also has an unusually high degree of specificity for the substrate angiotensin I. We report here the molecular cloning and nucleotide sequence of the gene and cDNA encoding human heart chymase, and determination of its entire deduced amino acid sequence. These data indicate that human heart chymase is highly homologous to other members of the chymase subfamily of chymotrypsin-like proteinases and, most likely, all evolved from a common ancestral gene. Potential regulatory elements found in the 5'-untranslated region of other chymases are also found in the human heart chymase gene. However, this gene lacks mast cell-specific sequences found in the 5'- and 3'-untranslated regions of the rat chymase II gene. In addition, human heart chymase contains clusters of unique amino acid sequences located at key positions likely involved in substrate binding, which may contribute to its high substrate specificity. These contrasting features of the human heart chymase gene and cDNA, and the potential determinants of its primary structure that underlie its unique functional characteristics are considered.
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PMID:Cloning of the gene and cDNA for human heart chymase. 189 11

Recent studies have led to a rapid expansion of knowledge concerning the structure and biology of the two major mast cell proteinases, tryptase and chymase. Tryptase is an abundant, trypsin-like enzyme found in the secretory granules of all human lung mast cells. The subunits of the heparin-associated tryptase tetramer appear to be the products of a multigene family whose intron-exon organization is unique and is not closely related to that of other mast cell or leukocyte serine proteinases. In vitro studies suggest that tryptases may participate in lung and airway responses by regulating airway neuropeptide activity, bronchomotor tone, and fibroblast mitogenesis. Mast cell chymases are chymotrypsin-like proteinases related closely to neutrophil cathepsin G and lymphocyte granzymes. The cDNA-derived structures of tryptase and chymase suggest that the two enzymes may differ in modes of activation from proenzyme forms, although the mature enzymes are packaged and released together. Chymase expression appears to be limited to a subset of human lung mast cells most prevalent in the airway submucosa. Possible roles for chymase include inactivation of sensory neuropeptides, regulation of submucosal gland secretion, and potentiation of histamine-induced vascular permeability.
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PMID:The structure and airway biology of mast cell proteinases. 202 78

Human mast cells can be divided into two subsets based on serine proteinase composition: a subset that contains the serine proteinases tryptase and chymase (MCTC), and a subset that contains only tryptase (MCT). In this study we examined both types of mast cells for two additional proteinases, cathepsin G and elastase, which are the major serine proteinases of neutrophils. Because human mast cell chymase and cathepsin G are both chymotrypsin-like proteinases, the properties of these enzymes were further defined to confirm their distinctiveness. Comparison of their N-terminal sequences showed 30% nonidentity over the first 35 amino acids, and comparison of their amino acid compositions demonstrated a marked difference in their Arg/Lys ratios, which was approximately 1 for chymase and 10 for cathepsin G. Endoglycosidase F treatment increased the electrophoretic mobility of chymase on SDS gels, indicating significant N-linked carbohydrate on chymase; no effect was observed on cathepsin G. Immunoprecipitation and immunoblotting with specific antisera to each proteinase revealed little, if any, detectable cross-reactivity. Immunocytochemical studies showed selective labelling of MCTC type mast cells by cathepsin G antiserum in sections of human skin, lung, and bowel. No labeling of mast cells by elastase antiserum was detected in the same tissues, or in dispersed mast cells from lung and skin. A protein cross-reactive with cathepsin G was identified in extracts of human skin mast cells by immunoblot analysis. This protein had a slightly higher Mr (30,000) than the predominant form of neutrophil cathepsin G (Mr 28,000), and could not be separated from chymase (Mr 30,000) by SDS gel electrophoresis because of the size similarity. Using casein, a protein substrate hydrolyzed at comparable rates by chymase and cathepsin G, it was shown that about 30% of the caseinolytic activity in mast cell extracts was sensitive to inhibitors of cathepsin G that had no effect on chymase. Hydrolytic activity characteristic of elastase was not detected in these extracts. These studies indicate that human MCTC mast cells may contain two different chymotrypsin-like proteinases: chymase and a proteinase more closely related to cathepsin G, both of which are undetectable in MCT mast cells. Neutrophil elastase, on the other hand, was not detected in human mast cells by our procedures.
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PMID:Identification of a cathepsin G-like proteinase in the MCTC type of human mast cell. 221 56

The protease inhibitor alpha-1-antichymotrypsin, which binds to chymotrypsin-like enzymes in a sodium dodecyl sulfate-resistant manner, has been shown recently to be both a normal constituent of brain and an integral component of the neuritic plaques that form in Down's syndrome and Alzheimer's disease. We have now identified in rat brain a Mr 25,000 alpha-1-antichymotrypsin-binding protein classified as a chymotrypsin-like protease by its inhibitor profile and substrate specificity. Release of 125I-labeled breakdown products from bands containing the protease in substrate-linked polyacrylamide gels was examined in parallel with hydrolysis of tetrapeptide chromogenic substrates in vitro to establish conditions under which the Mr 25,000 protease was the only activity being measured in vitro. The protease was completely membrane associated but was extractable using 1 M MgCl2; prior extraction of detergent- and low ionic strength-soluble proteins from membranes was used to increase its specific activity. The formation of sodium dodecyl sulfate-resistant bonds between human alpha-1-antichymotrypsin and the protease (kassoc = 2.9 X 10(6) M-1 s-1) was used to titrate the concentration of free protease solubilized from membranes. The protease cleaved both succinyl-Ala-Ala-Pro-Phe-p-nitroanilide, and methoxy-succinyl-Ala-Ala-Pro-Met-p-nitroanilide, the latter being of interest because cleavage after a methionine residue is predicted to generate the amino terminus of the neuritic plaque component beta-amyloid from its precursor protein. In fact, the solubilized protease degraded 90% of membrane-associated beta-amyloid precursor protein detected by Western blot analysis. The protease was kinetically distinct from both chymotrypsin and cathepsin G in direct comparisons and did not match kinetic values published for the rat mast cell proteases against comparable substrates; we therefore refer to the protease with the descriptive acronym clipsin (for chymotrypsin-like protease). Proteases similar to and potentially identical to clipsin were detected by enzymography in other organs from rat (most notably spleen and adult lung). The enzyme in brain was distinguished by a narrow window of elevated activity surrounding postnatal day 5, which was 12-14-fold higher than levels in day 1 or adult brain. Because independent lines of evidence suggest that a brain chymotrypsin-like protease may be involved in the etiology of Down's syndrome and Alzheimer's disease, clipsin is discussed as a candidate for such a role.
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PMID:Clipsin, a chymotrypsin-like protease in rat brain which is irreversibly inhibited by alpha-1-antichymotrypsin. 230 81

The serine proteases tryptase and chymase are present in human pulmonary mast cells. About 10-100 times more tryptase than chymase is found in these cells. However, a clear physiological role for both enzymes remains to be elucidated; angiotensin processing has been proposed as one possible function of chymase. A dose-dependent inhibition of A23187-induced histamine release from dispersed human lung mast cells was observed after pretreatment with the serine protease inhibitor diisopropylfluorophosphate (DFP) or the chymotrypsin-like enzyme inhibitor N-tosyl-L-phenylalanine chloromethylketone (TPCK) but not with the trypsin-like enzyme inhibitor N-tosyl-L-lysine chloromethylketone (TLCK). These results indicate that a chymase is probably an important factor in a late phase of human lung mast cell activation.
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PMID:The effect of serine esterase inhibitors on ionophore-induced histamine release from human pulmonary mast cells. 245 88

We tested four synthetic substances for their histochemical value to demonstrate the catalytic activities of chymase or tryptase in mast cells in sections of human gut. Both Suc-Ala-Ala-Phe-4 methoxy-2-naphthylamide (MNA) and N-acetyl-L-methionine-alpha-naphthyl ester (alpha-N-O-Met) reacted with chymase but not tryptase in mast cells. Conversely, D-Val-Leu-Arg-MNA and Z-Ala-Ala-Lys-MNA were hydrolyzed by mast cell tryptase but not chymase. These results were confirmed by use of two inhibitors of chymotrypsin-like activity, chymostatin and Z-Gly-Leu-Phe-chloromethyl ketone (CK) and two inhibitors of trypsin-like activity, Tos-Lys-CK and D-Val-Leu-Arg-CK. Excellent staining reactions were obtained on cryostat sections of unfixed or aldehyde-fixed tissues and on paraffin sections of Carnoy-fixed tissues. For chymase, however, Suc-Ala-Ala-Phe-MNA is preferred on cryostat sections because it is more specific. On paraffin sections alpha-N-O-Met is preferred because other cells are not then stained. For tryptase, Z-Ala-Ala-Lys-MNA was more selective and more specific and is the preferred general purpose substrate on cryostat sections of aldehyde-fixed tissues and for paraffin sections. D-Val-Leu-Arg-MNA is the preferred substrate for cryostat sections of unfixed tissue. Only a limited number of mast cells showed a reaction for chymase, and these occurred mainly in the submucosa. All mast cells, however, gave a reaction for tryptase, and we recommend the use of either substrate for this enzyme for routine detection of mast cells in human tissues. Double staining for the two main mast cell proteases is most conveniently undertaken on paraffin sections of Carnoy-fixed tissues using MNA substrates for tryptase and alpha-N-O-Met for chymase.
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PMID:Enzyme histochemical discrimination between tryptase and chymase in mast cells of human gut. 264 38

A mast cell granule proteinase was purified from isolated ovine mucosal mast cells by cation exchange chromatography, which defined the conditions for enzyme purification from sheep gastric mucosae. Antibodies raised against the proteinase were used in subsequent purification procedures which yielded 78 micrograms of enzyme per 5 g wet wt of abomasal tissue. Immuno-histochemistry confirmed that mucosal mast cells were the source of the enzyme. The proteinase had chymotrypsin-like esterase activity, with a molecular weight between 19,000 and 25,000.
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PMID:The isolation and purification of a proteinase with chymotrypsin-like properties from ovine mucosal mast cells. 309 19

Serine class proteinases with trypsin-like and chymotrypsin-like specificity were purified from dog mastocytoma tissue. An antiserum was produced against the chymotrypsin-like proteinase. The antiserum reacted with mast cells in skin sections prepared from normal dogs consistent with the proteinase being a mast cell constituent. The antiserum also cross-reacted with the major chymotrypsin-like proteinase isolated from normal dog skin and partially cross-reacted with human skin chymase. No cross-reaction was detected with rat chymase. The trypsin-like proteinase from dog mastocytoma tissue was similar to tryptase isolated from human skin. It had a similar subunit structure, was not inhibited by many protein proteolytic enzyme inhibitors, bound to heparin, and reacted strongly with antiserum against human tryptase. Antiserum against human tryptase also reacted with mast cells in skin sections prepared from normal dog skin. No immunocytochemical labeling of rat skin mast cells was observed with anti-human tryptase. These studies establish the presence of a trypsin-like and chymotrypsin-like proteinase in dog skin mast cells and provide immunological evidence which suggests that both proteinases are more closely related to human than rat mast cell proteinases. These immunological and biochemical relationships are important when comparing the roles of these proteinases in different animals.
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PMID:Purification and identification of two serine class proteinases from dog mast biochemically and immunologically similar to human proteinases tryptase and chymase. 312 77


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