Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The calcium-dependent cell-adhesion molecule uvomorulin is a member of the cadherin gene family. Recent studies on the homophilic binding of molecules from neighbouring cells have shown that the amino-terminal part of these proteins plays an important role in the adhesive mechanism. We show here that the epitope for monoclonal antibody DECMA-1, capable of blocking uvomorulin function, is located close to the membrane proximal part of the extracellular domain. To test the effect of structural changes in this membrane proximal region on the adhesive function of uvomorulin, we have studied the cluster of cysteine residues located in the vicinity of the DECMA-1 epitope. Treatment of cells with the reducing agent dithiothreitol (DTT) cleaved the di-sulphide bonds in uvomorulin and affected the adhesive properties of cells. Close cell-cell contacts accompanied by cell flattening and changes in cell shape were blocked by DTT; however, cell aggregation was not inhibited. Consistent with this, uvomorulin became more susceptible in its membrane proximal part to trypsin digestion after treatment with DTT, indicating that conformational changes in this region of the molecule affect the adhesive function. These results suggest that the membrane proximal region of uvomorulin is involved in the adhesive mechanism.
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PMID:A possible new adhesive site in the cell-adhesion molecule uvomorulin. 171 Sep 17

B cell differentiation requires adhesion of B cell progenitors to bone marrow (BM) or fetal liver stroma. We show that B lymphoid cells can adhere to the BM stroma cell line CS 1.3, in vitro. Two monoclonal antibodies, SAB-1 and SAB-2, inhibited the adhesion of a B220+ progenitor B cell line but did not interfere with the binding of cytoplasmic mu chain-positive pre-B cells or mature B cells to the BM stromal cell line. Injection of both SAB-1 and SAB-2 antibodies into pregnant mice reduced by 90% the number of B220+n B lineage cells in the livers of their embryos. Livers from such embryos also were virtually devoid of cells able to give rise to B cell colonies in soft agar cultures (CFU-preB). Either antibody separately had no effect. Flow cytometry analysis show that SAB-1 is present on CS 1.3 stroma cells and on a pre-B cell line while SAB-2 is present on pro-B and pre-B cell lines, but not on CS 1.3 stromal cells. SAB-1 and SAB-2 react with different molecules and neither antibody seems to recognize CD44, and adhesion molecule that may also participate in B cell differentiation. Proteinase K and trypsin can digest both SAB-1 and SAB-2 antigens from viable cells suggesting that both are cell surface proteins. We propose that antibodies SAB-1 and SAB-2 probably recognize novel cell-cell adhesion molecules, and that these molecules are involved in the interactions between B cell progenitors and stroma cells.
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PMID:Monoclonal antibodies that block adhesion of B cell progenitors to bone marrow stroma in vitro prevent B cell differentiation in vivo. 188 55

Macrophage adhesion molecule (MAM), an abundant surface molecule which functions in the adhesion and spreading of guinea pig macrophages on surfaces, is characterized as a heterodimer of the trypsin- and plasmin-sensitive glycopeptide gp160 (MAM-alpha) and the glycopeptide gp93 (MAM-beta). The density of MAM molecules is estimated at 630,000 per macrophage on the basis of quantitative binding of 125I-labeled monoclonal antibody. The glycopeptide subunits display microheterogeneity on isoelectrofocusing; the pI is 5.8-6.3 for gp160 (MAM-alpha) and 6.4-7.0 for gp93 (MAM-beta). A neutrophil gp160, gp93 molecule was shown to be indistinguishable from macrophage MAM on the basis of electrophoresis, isoelectrofocusing, and reactivity with 10 monoclonal antibodies. A related heterodimer of gp93 associated with a larger, antigenically different glycopeptide (gp180,gp93) was identified on circulating lymphocytes. Cumulative properties indicate that MAM is the guinea pig analogue of human Mo1 and mouse Mac-1.
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PMID:Characterization of macrophage adhesion molecule. 296 69

Macrophage adhesion molecule (MAM) is a surface heterodimer consisting of the trypsin- and plasmin-sensitive glycopeptide gp160 (MAM-alpha) and the glycopeptide gp93 (MAM-beta). MAM, which is the guinea pig analogue of Mo1 and Mac-1, was purified from detergent lysates of peritoneal neutrophils by lentil lectin chromatography and M2-antibody chromatography. The pure heterodimer molecule was dissociated by acidic conditions (pH 3.5), and MAM-alpha and MAM-beta were separated by M7-antibody chromatography. MAM-beta is an approximately 640 amino acid residue polypeptide with exceptionally high cysteine content. At 7.2 residues per 100 amino acids, Cys/2 of MAM-beta is more than 3 times the mean for 200 purified proteins. Reactivity with six beta-subunit-specific monoclonal antibodies recognizing at least four epitopes demonstrated that intrapeptide disulfide bonds are required to maintain the structure of MAM-beta. All six antibodies failed to react when MAM-beta was treated with reducing agents. MAM-beta is 18% carbohydrate; the major monosaccharides are mannose, N-acetylglucosamine, galactose, and sialic acid. MAM-beta is estimated to contain five to six N-linked carbohydrate units. MAM-alpha is an approximately 1100-residue polypeptide with lower Cys/2 content (2.0 residues per 100 amino acid residues). MAM-alpha is 21% carbohydrate. The major monosaccharides are mannose, N-acetylglucosamine, galactose, and sialic acid; the mannose content is higher in MAM-alpha than MAM-beta. MAM-alpha is estimated to contain 12 N-linked carbohydrate units.
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PMID:Purification, composition, and structure of macrophage adhesion molecule. 334 44

E-cadherin is a Ca2+-dependent cell-cell adhesion molecule identified as a glycoprotein with a molecular weight (MW) of 124,000. To study the role of the sugar moieties of this adhesion molecule, we tested the effect of tunicamycin on aggregation mediated by E-cadherin of teratocarcinoma cells. Immunoblot analysis using a monoclonal antibody to E-cadherin showed that in cells treated with tunicamycin this adhesion molecule is converted into two forms with MW of 118,000 and 131,000. The smaller one was exposed on the cell surface and showed a trypsin sensitivity characteristic to E-cadherin, suggesting that this is the peptide moiety of E-cadherin whose glycosylation with N-linked oligosaccharides was blocked by tunicamycin. The larger one was not removed by trypsin treatment of cells, suggesting an intracellular location. These tunicamycin-treated cells aggregated in a Ca2+-dependent manner, and the aggregation was inhibited by a monoclonal antibody to E-cadherin. These results suggested that N-linked oligosaccharides are not involved in the functional sites of this adhesion molecule.
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PMID:N-linked oligosaccharides are not involved in the function of a cell-cell binding glycoprotein E-cadherin. 376 62

Teratocarcinoma cells have a Ca2+-dependent cell-cell adhesion site (t-CDS) that is unique in being inactivated with trypsin in the absence of CA2+ but not in the presence of Ca2+. Fab fragments of antibodies raised against teratocarcinoma F9 cells dissociated by treatment with trypsin and calcium (anti-TC-F9) inhibit the aggregation of teratocarcinoma cells mediated by t-CDS. This inhibitory effect of Fab is removed when anti-TC-F9 is absorbed with F9 cells treated with trypsin and calcium (TC-F9), but not when it is absorbed with F9 cells treated with trypsin and EGTA (TE-F9). Comparisons of cell-surface antigens reactive to anti-TC-F9 in TC-F9 cells with those in TE-F9 cells reveal that only one component, with an approximate molecular weight of 140,000 (p140), is detected specifically on the surface of TC-F9 cells. When TC-F9 cells are retrypsinized in the absence of CA2+, a substance with an approximate molecular weight of 34,000 (p34) is released that can neutralize the aggregation-inhibitory effect of the Fab. This p34 interferes with the immunoprecipitation of p140 with anti-TC-F9, suggesting that p34 is a tryptic fragment of p140. Anti-TC-F9 Fab causes the dissociation of the monolayers of teratocarcinoma cells. This effect is removed by absorption of the Fab with p34 as well as with TC-F9 cells, but not with TE-F9 cells. These results suggest that p140 is essential for the function of t-CDS, and that this is an actual cell-adhesion molecule active in the establishment of monolayers of teratocarcinoma cells.
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PMID:Teratocarcinoma cell adhesion: identification of a cell-surface protein involved in calcium-dependent cell aggregation. 706 Jan 28

Allergic rhinitis is the sixth most prevalent chronic health condition in the United States. To study the pathogenesis of the allergic response, we have used a model of nasal provocation with antigen. During the initial reaction of an allergic subject to allergen provocation, increases occur in the levels of histamine, tryptase, and prostaglandin D2. This pattern of mediator release, combined with histologic evidence of mast-cell degranulation, strongly supports the role of the mast cell in the acute allergic reaction. The response to antigen, however, does not end with mast-cell degranulation. Hours after challenge we observed the spontaneous recurrence of symptoms and increased responsiveness to antigenic and nonantigenic stimuli. Our central hypothesis is that cellular infiltration and activation after antigen challenge are responsible for the observed increase in nasal reactivity. The predominant cells in nasal lavage 24 hours after challenge are eosinophils and neutrophils, whereas the predominant cell in the mucosa is the CD4+ lymphocyte. An early step in the movement of cells from the peripheral blood involves adhesion between circulating leukocytes and the endothelium. Evidence suggests that vascular endothelial adhesion molecule may be responsible in part for the selective adherence of eosinophils to the endothelium.
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PMID:Observations on the response of the nasal mucosa to allergens. 752 55

Mast cells are granule-containing secretory cells which are distributed preferentially about the microvascular bed in oral mucosa. This work examined the contribution of mast cell mediators to inflammation in the oral cavity. Mast cells in oral tissues expressed the serine proteases, tryptase and chymase, with a minor subpopulation being chymase-negative. Mast cells contained the cytokine tumour necrosis factor-alpha (TNF) in their granules. Degranulation of mast cells was a consistent feature of inflammatory lesions (lichen planus, gingivitis, pulpitis, periapical inflammation). In lichen planus, intracellular stores of TNF were depleted, and expression of mRNA for TNF was upregulated, indicating ongoing production and release of the cytokine. The density of mast cells in tissue compartments was related to the level of expression of E-selectin, an endothelial adhesion molecule which is known to be induced in skin by TNF derived from degranulating mast cells. Further attention should be directed toward the role of mast cell products, particularly TNF, in inflammation in the oral cavity.
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PMID:Relationship between mast cell degranulation and inflammation in the oral cavity. 756 63

A method for the isolation and long-term culture of human microvessel endothelial cells from mammary adipose tissue (HuMMEC) obtained at breast reduction surgery has been developed. Pure cultures of HuMMEC were isolated by sequential digestion of the fat with collagenase and trypsin followed by specific selection of microvessel fragments with Ulex europaeus agglutinin-1 coated magnetic beads (Dynabeads). The resulting cells formed contact-inhibited monolayers on gelatin and fibronectin substrates and capillary-like "tubes" on Matrigel; they also expressed von Willebrand factor, angiotensin-converting enzyme, and accumulated acetylated low density lipoprotein. Further immunofluorescence characterization revealed the presence of antigens for the endothelial cell specific monoclonal antibodies EN4 and H4-7/33. In addition, the origin of these cells was confirmed by the demonstration of the cell adhesion molecules, platelet endothelial cell adhesion molecule-1 (CD31), and endothelial leukocyte adhesion molecule-1 (ELAM-1/E-selectin) upon stimulation with tumor necrosis factor (TNF) alpha. HuMMEC were found to express-1 ELAM-1 at lower levels of TNF alpha (< 10 ng/ml) than required by human umbilical vein endothelial cells. These cells should provide a useful in vitro model for studying various aspects of microvascular biology and pathology.
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PMID:Isolation and characterization of microvessel endothelial cells from human mammary adipose tissue. 768 48

The stimulated release of von Willebrand factor (vWF) from endothelial cells by secretagogues such as thrombin is associated with the translocation of Weibel-Palade bodies to the cell membrane and the surface expression of P-selectin (also known as GMP 140, PADGEM and CD 62). P-selectin, which is stored in Weibel-Palade bodies, is a neutrophil and monocyte adhesion molecule important in the initiation of inflammation. We have developed a simple assay for the detection of P-selectin on endothelial cells using indirect immunofluorescence and flow cytometry and have confirmed that this is temporally related to vWF release. The assay has been used to demonstrate that IL-1 does not cause Weibel-Palade body degranulation but that trypsin does. This has implications for the use of passaged endothelial cells in the study of vWF release and the assay has numerous possible applications in study of mechanisms of stimulated vWF release.
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PMID:von Willebrand factor release and P-selectin expression is stimulated by thrombin and trypsin but not IL-1 in cultured human endothelial cells. 769 90


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