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)

When rat adrenal whole capsules, containing the zona glomerulosa, were incubated, addition of the protein kinase C inhibitors TMB-8 (10 mumol/l), W7, H7, polymyxin-B and sphingosine (all 1 mumol/l) was found to inhibit the steroidogenic response to trypsin. Aldosterone and 18-hydroxycorticosterone were strongly, and corticosterone moderately, affected, while the production of 18-hydroxydeoxy-corticosterone was neither stimulated by trypsin nor inhibited by the protein kinase C inhibitors. Addition of neomycin, which prevents substrate interaction with phospholipase C, also inhibited the response to trypsin, while addition of phospholipase C itself stimulated aldosterone, 18-hydroxycorticosterone and corticosterone production with the same tissue sensitivity as trypsin. Addition of phospholipase A2 had no effect. Direct assay of protein kinase C activity showed that trypsin stimulation effected the translocation of Ca2+/phospholipid-activated protein kinase C from the cytosolic to the membrane fraction. When glomerulosa tissue was incubated with [32P]ATP, and cytosolic proteins were subjected to isoelectric focusing on polyacrylamide gels, autoradiography showed that incorporation of 32P into several protein components was increased by trypsin stimulation. It was concluded that trypsin exerts its stimulatory effects on steroidogenesis by activating protein kinase C; not, however, by generating the Ca2+/phospholipid-independent fragment, but possibly by enhancing the activity of phospholipase C.
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PMID:Trypsin stimulation of aldosterone and 18-hydroxycorticosterone production by rat adrenal zona glomerulosa tissue is mediated by activation of protein kinase C. 239 25

Evidence presented demonstrates a covalent attachment of a phospholipid to bovine myelin basic protein. Partial characterization of the phospholipid moiety was performed on myelin basic protein obtained from 32P-phosphorylated whole myelin that was first delipidated by two ether/ethanol (3:2 v/v) extractions, ether extraction, and acetone extraction and then purified by preparative sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The myelin basic protein was precipitated with aqueous acetone and treated with proteases. Treatment with carboxypeptidase Y or trypsin for several hours released a lipophilic fragment, which was purified by reverse-phase high-performance liquid chromatography to yield two "lipopeptides". Such lipopeptides were obtained from both the major and minor myelin basic proteins of rat and bovine brain. Treatment with either mild base or phospholipase C removes the lipophilic character of the peptide fragment. The lipophilic fragment is a substrate for phospholipase D, but it does not comigrate on thin-layer chromatography with any 32P-labeled lipid obtained from myelin incubated with [gamma-32P]ATP. Polyphosphoinositides were shown to be released by mild acid treatment of myelin basic protein that had been extracted with organic solvent and then purified by SDS-polyacrylamide gel electrophoresis. Along with the fact that inositol monophosphate was identified in the partial acid hydrolysate of the lipopeptide, we have concluded that polyphosphoinositide (phosphatidylinositol 4-phosphate and/or phosphatidylinositol 4,5-bisphosphate) was the original phospholipid portion of the lipopeptide.
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PMID:Colvalent linkage of phospholipid to myelin basic protein: identification of phosphatidylinositol bisphosphate as the attached phospholipid. 242 99

Intact bloodstream forms of Trypanosoma brucei brucei, T.b. gambiense, and T.b. rhodesiense and procyclic forms of T.b. brucei and T.b. gambiense were incubated in trypsin, solubilized for gel electrophoresis, and analyzed for removal of surface molecules. Silver-stained gels and transfer blots probed with horseradish peroxidase-conjugated or radiolabeled lectins revealed that only three glycoproteins, Gp120p, Gp91p, and Gp23p, were removed from the surface of procyclic forms by trypsin. The variant specific glycoproteins, Gp23b, Gp120b, and in some clones Gp91b were surface molecules cleaved from bloodstream forms. Greater than 90% of the variant specific glycoprotein (VSG) was removed from the surface of all clones studied within 1 hr following the addition of trypsin. The removal of VSG was coincident with appearance of 37 to 50 kDa glycopeptide fragments of VSG with different clones yielding different sized fragments. Detailed kinetic analysis of proteins from whole cell extracts and supernatants of the DuTat 1.1 clone of T.b. rhodesiense using concanavalin A (Con A) and polyclonal antibodies revealed that three major VSG fragments were released during trypsinization. The electrophoretic mobility of the three VSG fragments of DuTat 1.1 was not altered when samples were boiled in sodium dodecyl sulfate to inhibit the endogenous phospholipase C. Antiserum to the cross-reactive determinant bound to intact VSG, but did not bind VSG fragments. Thus, the major Con A binding fragments of DuTat 1.1 VSG and perhaps those of the other clones we studied were probably derived from the N-terminal domain of the molecule. The data suggest that VSG is cleaved by trypsin in situ at the hinge region, but remains attached to the cell surface via weak interaction with neighboring molecules.
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PMID:Trypanosoma brucei sspp.: cleavage of variant specific and common glycoproteins during exposure of live cells to trypsin. 245 21

Serine protease inhibitors with a specificity for trypsin inhibit interferon-gamma (INF-gamma)-induced HLA-DR expression on a hybrid human epidermal cell line (H12), dermal fibroblasts, and primary keratinocytes. Protease inhibitors with a specificity for chymotrypsin or papain fail to inhibit IFN-gamma. The inhibitory effect of the trypsin inhibitors is similar to that of glucocorticoids in that it is a transient event, fading with length of exposure to IFN-gamma, and is reversed by the addition of dibutyryl cyclic AMP (dbcAMP) and phospholipase C(PLC) from Clostridium perfringens. In H12 cells, dbcAMP and PLC enhance the IFN-gamma induction of HLA-DR, but do not induce in the absence of INF-gamma. Evidence suggests that the protease inhibitors, as well as dbcAMP and PLC, may modulate HLA-DR expression at a post-translational site as well as during IFN-gamma signal transduction. These results suggest that trypsin-like protease activity may be required for cellular HLA-DR antigen expression following exposure to IFN-gamma.
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PMID:Trypsin inhibitors inhibit induction by interferon-gamma of HLA-DR antigen expression on human skin cells. 247 85

Mouse diaphragm contractures induced by Cu2+, caffeine and selenite were studied comparatively. Both Cu2+- and caffeine-contractures were produced rapidly and relaxed spontaneously; the selenite-contracture occurred after a latent period of about 45 min and lasted for more than 3 hr. All contractures were myogenic, since neither d-tubocurarine nor tetrodotoxin prevented them. The susceptibility of these contractures to the depletion and replenishment of Ca2+ differed: the Cu2+-contracture increased proportionally with rising extracellular Ca2+ concentrations ranging from 2.5 to 12.5 mM and were abolished by 5 mM EGTA. Caffeine- and selenite-contractures were not affected by changes in extracellular Ca2+ concentration. The caffeine-contracture was abolished by EGTA in high concentration (30 mM) and the selenite-contracture was inhibited by 50 mM EGTA. After removal of Ca2+ with 5 mM EGTA, followed by replacement with 2.5 mM Ca2+ for 1 min, the Cu2(+)-contracture was fully restored. Caffeine- and selenite-contractures were restored only after a longer period (10-20 min) of re-exposure to Ca2+. These findings suggest that the Cu2(+)-contracture is dependent on external Ca2+ and probably caused by an increasing Ca2+ entry through sarcolemma. Caffeine- and selenite-contractures apparently result from internal Ca2+ release by sarcoplasmic reticulum. Substitution of either Sr2+ or Co2+ for Ca2+ fully supports the Cu2(+)-contracture. 45Ca2+ uptake and calcium content of the diaphragm were markedly increased by Cu2+ but not by selenite. Furthermore, the Cu2(+)-contracture was inhibited by exposing the outer membrane to trypsin, phospholipase C or saponin. The selenite-contracture was inhibited only by trypsin. The caffeine-contracture was unaffected by these treatments. These results support the notion that the Cu2(+)-contracture is induced by an increased entry of Ca2+ through the outer membrane. Cu2(+)-, caffeine- and selenite-contractures were respectively abolished, potentiated and unaffected by chronic denervation of the diaphragm. This and the other findings provide evidence that Cu2(+)-, caffeine- and selenite-contractures are induced in mouse diaphragm muscle via different sites of action.
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PMID:Studies on contractures induced in mouse diaphragm by caffeine and cupric and selenite ions. 251 19

The glucose polymer of PC12 cells (Rasilo, M.-L. and Yamagata, T., 1988, FEBS Letters 227, 191-194 and Rasilo, M.-L. and Yamagata, T., 1988, Journal of Biochemistry, 104, 742-754) was found to be located on the cell surface. The polymer was liberated from the galactose-labeled cells with a trypsin treatment: maximally 65% of the glucose polymer was liberated, compared with 36% of the large glycopeptides. Even when the cells were incubated with the saline about one fourth of the polymer moved into the solution, but less than 8% of the large glycopeptides. Phosphatidyl inositol-specific phospholipase C failed to liberate the polymer.
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PMID:The glucose polymer of PC12 cells is susceptible to trypsinization. 253 15

Phosphoinositide phospholipase C activity has been measured in erythrocyte membranes from age-matched control and CF subjects. Inositol phospholipids were labelled with [3H]myo-inositol and control experiments demonstrated that the [3H]-labelled products released by incubation of membranes with Ca2+ were derived specifically from erythrocytes (a) by purification of erythrocytes on cellulose columns, (b) by demonstration that the phospholipase C activity was inhibited by 10 mmol/l neomycin but not by 1 mmol/l p-methylsulphonylfluoride. The [3H]-labelled products were shown to be inositol phosphates by their elution from anion-exchange columns. Membranes from CF patients showed increased phospholipase C activity compared to controls which did not correlate with the degree of [3H]inositol labelling of the membranes, with pancreatic function as assessed by serum immunoreactive trypsin or with medications taken by the patients.
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PMID:Increased phosphoinositide breakdown by phospholipase C in erythrocyte membranes from patients with cystic fibrosis. 254 51

Thrombin stimulates polyphosphoinositide hydrolysis in embryonic chick heart cells and in 1321N1 astrocytoma cells and increases intracellular Ca2+ in the 1321N1 cells. The serine protease trypsin mimics these actions in a dose-dependent fashion, whereas the proteolytically inactive thrombin derivatives diisopropyl fluorophosphate-thrombin (DIP-thrombin) and D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone-thrombin (PPACK-thrombin) are ineffective in this regard. The phosphoinositide responses to thrombin or trypsin and the muscarinic agonist carbachol are additive, but no additivity is observed between the responses to thrombin and trypsin. Unlike the response to carbachol, the phosphoinositide and Ca2+ responses to thrombin and trypsin desensitize, with no recovery of the calcium response even when Ca2+ stores are replenished. Cross-desensitization of phospholipase C activation and calcium mobilization between these proteases is also observed. In addition, PPACK-thrombin, which elicits no response itself, effectively inhibits trypsin-stimulated phosphoinositide hydrolysis. It is proposed that thrombin and trypsin act through the same receptor. Proteolysis appears to be important in the mechanism by which these agonists elicit phosphoinositide hydrolysis, calcium mobilization, and, perhaps, subsequent receptor desensitization.
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PMID:Thrombin and trypsin act at the same site to stimulate phosphoinositide hydrolysis and calcium mobilization. 254 47

Ca2+ dependent polyphosphoinositide phospholipase C (PLC) activity in cardiac sarcolemma hydrolyzed both endogenous and exogenous phosphatidylinositol 4-phosphate (PIP) and phosphatidylinositol 4,5-bisphosphate (PIP2) with an associated increase in inositol bisphosphate (IP2). Dialyzed cytosol and certain fractions of cytosol isolated by anion exchange or gel filtration chromatography activated sarcolemmal PLC activity by approx. 100%. The PLC activator eluted with an apparent molecular weight of 160 Kdal on a Sephacryl 300 column and was destroyed by heat or trypsin treatment. Exogenous 3H-PIP2 was not hydrolyzed by cytosolic fractions containing sarcolemmal PLC activator. These studies demonstrate that the polyphosphoinositide PLC in cardiac sarcolemma is regulated by a cytosolic protein.
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PMID:A cytosolic protein activator of cardiac sarcolemmal phosphoinositide phospholipase C. 254 98

The possibility that thrombin-induced platelet reactivity could occur via both a receptor-related and a proteolytic process was examined. Thrombin elicited the formation of considerably more [32P]phosphatidic acid (an index of phospholipase C catalysed phosphoinositide metabolism) than did platelet activating factor, 5-hydroxytryptamine, ADP, and the thromboxane A2 analogue EP171, when these agents were added either alone or in combination. Co-addition of thrombin and EP171 did not evoke significantly more [32P]phosphatide acid than did thrombin alone. The protease inhibitor leupeptin, decreased but did not abolish [32P]phosphatidic acid formation elicited by either thrombin alone or thrombin in combination with EP171. The serine protease, trypsin, stimulated an increase in [32P]phosphatidic acid and this effect was additive with that of EP171. This augmentation by trypsin of EP171-induced [32P]phosphatidic acid formation was inhibited by leupeptin. These results are consistent with the concept that thrombin-induced activation of phospholipase C occurs by two distinct mechanisms: one via proteolysis, which is sensitive to leupeptin, and the other via receptor activation, a process shared by EP171. The individual components of this dual mechanism can be mimicked by the co-addition of a receptor-directed agonist (EP171) and a proteolytic agent (trypsin).
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PMID:Evidence for two mechanisms of thrombin-induced platelet activation: one proteolytic, one receptor mediated. 255 47


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