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)

Aminopeptidase (AP) A, B, and M, gamma-glutamyltranspeptidase (GGT), endopeptidase I and II, membrane-associated endopeptidase I and II, dipeptidylaminopeptidase (DAP) I, II, and IV, trypsin and chymotrypsin were investigated with 4-methoxy-2-naphthylamine (MNA) substrates and ester proteinases with n-acetyl-L-methionine-1-naphthylester as substrate in the digestive tract of laboratory rodents. Biochemically, proteinases and ester proteinases show different activities in the salivary glands, esophagus, stomach, liver, pancreas, duodenum jejunum, ileum, and colon; sex differences in proteinase and ester proteinase activity were measured, especially in the submandibular gland of rats and mice. Histochemically these enzymes are preferentially localized in surface membranes, lysosomes, secretion granules, and Golgi apparatus of cells of the endocrine and exocrine secretory system, resorptive system and immune system of the digestive tract. Besides the general occurrence of lysosomal (DAP I and II, single cell types and functional units of these systems possess their own individual proteinase and ester proteinase equipment. The cells of the granulated tubules of rat and mouse submandibular gland contain endopeptidase I and ester proteinases, its acinar cells DAP IV, the chief cells of the stomach APA, enteroendocrine cells APA, APM, and DAP II, hepatocytes DAP IV or GGT and DAP IV, lymphocytes GGT and DAP IV, and enterocytes trypsin, chymotrypsin, and membrane-associated endopeptidase I and II. Sex differences in proteinase activity are most conspicuous in the granulated tubule cells of the rat and mouse submandibular gland. The data suggest that proteinases and ester proteinases are involved in specific functions of the cells of the digestive tract. Furthermore, myoepithelial cells, smooth muscle cells of the muscular layer of the stomach and intestine, connective tissue cells (including mast cells) and fibers, nerve cells of the myenteric plexus and the capillary bed of the digestive organs are equipped with some of these proteinases and with ester proteinases and show organ differences.
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PMID:Investigation of proteinases in the digestive tract using 4-methoxy-2-naphthylamine (MNA) substrates. 701 83

The biosynthetic origin was investigated of gp160, the trypsin- and plasmin-sensitive surface glycoprotein of caseinate-elicited macrophages from guinea pigs. Biosynthesized surface components were analyzed by reacting [35S]methionine-labeled macrophages with trinitrobenzene sulfonic acid and purifying trinitrophenyl-substituted surface proteins by immunoprecipitation. Identification of gp160 was based on its molecular weight and unique trypsin sensitivity. In addition, [35S]methionine-labeled surface and intracellular glycoproteins were purified by Lens culinaris lectin affinity chromatography. Both purification procedures demonstrated that gp160 is biosynthesized by elicited macrophages in culture. gp160 was first detected on the cell surface 60-80 min after pulse labeling; transit to the cell surface was almost maximal at 3 h. No evidence was found for intracellular accumulation of mature gp160, i.e. in time course experiments all [35S]methionine-labeled gp160 was sensitive to trypsin treatment of intact cells. However, [35S]methionine-labeled gp160 was not detected in pulse-labeled macrophages until 60 min of nonradioactive chase incubation, indicating the existence of a precursor form.
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PMID:Biosynthesis of gp160, the major trypsin-sensitive surface glycoprotein of macrophages. 707 83

Macrophages secrete a large number of proteases, implying in vivo exposure of the cell surface to proteolytic conditions. Mild trypsin treatment of 125I-labeled guinea pig peritoneal macrophages preferentially cleaves one surface component of apparent 160,000 mol wt. Similar trypsin treatment of macrophages with 3H-labeled carbohydrate surface moieties also cleaves a single 3H-labeled 160,000 mol wt glycoprotein, referred to as gp160. Nonreducing sodium dodecyl sulfate (SDS)-electrophoresis established that gp160 of trypsinized cells remains assembled in the membrane as a multichain disulfide-bonded molecule. gp160 was purified by detergent extraction, L. culinaris lectin affinity chromatography and DEAE-cellulose chromatography. The corresponding molecule from trypsinized cells was purified by the same procedure. Reducing SDS-electrophoresis of purified trypsinized 125I-labeled gp160 revealed two proteolytic fragments with apparent molecular weights of 85,000 and 71,000. Thus, mild trypsin treatment of macrophages preferentially cleaves a single surface protein, possibly at a single site. Because the two fragments of gp160 are accessible to lactoperoxidase and trypsin, both must be exposed on the membrane surface. The reactive carbohydrate site was found on the 85,000 mol wt fragment, which alone contains the 3H-label introduced into intact cells by neuraminidase, galactose, oxidase, and [3H]KBH4.
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PMID:Macrophage component gp160, a major trypsin-sensitive surface glycoprotein. 745 50

We recently purified the calcium-independent processing protease named viral envelope glycoprotein maturase (VEM), that converts human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein precursor gp160 to gp120 and gp41, from the human CD4+ T cell line, Molt-4 clone 8 [Kido, H., Kamoshita, K., Fukutomi, A., and Katunuma, N. (1993) J. Biol. Chem. 268, 13406-13413]. In this report, we deal with the inhibitor specificity and calcium requirement for intracellular gp160 processing in cultured HeLa cells and human CD4+ lymphocytes. Processing of gp160 in these cells infected with recombinant vaccinia virus encoding the gp160 gene was not affected by intracellular calcium depletion induced by the calcium ionophore A23187 and EGTA or by intracellular calcium administration. Processing of gp160 by the purified VEM in vitro was not inhibited by EDTA, EGTA, or the metallo-protease inhibitor phosphoramidon, but was specifically inhibited by a substrate analog, decanoyl-RVKR-chloromethylketone, and the trypsin-type protease inhibitors aprotinin, HI-30, and diisopropyl fluorophosphate (DFP). It was also inhibited by E-64 and thiol reagents. But intracellular gp160 processing was inhibited only by permeable, low molecular mass inhibitors of VEM, such as DFP, E-64, and thiol reagents. Syncytium formation induced by cell surface gp120 was also inhibited by permeable inhibitors of VEM. Taken together, our results indicate that calcium ions may not be essential for intracellular gp160 processing and so HIV-1 gp160 induced by recombinant vaccinia virus may be processed mainly by a protease(s) that does not require calcium ions, such as VEM in these cells.
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PMID:Calcium requirement and inhibitor spectrum for intracellular HIV type 1 gp160 processing in cultured HeLa cells and CD4+ lymphocytes: similarity to those of viral envelope glycoprotein maturase. 749 Feb 67

Proteolytic processing of the human immunodeficiency virus type 1 (HIV-1) envelope (Env) precursor glycoprotein (gp160) to produce the mature gp120 and gp41 proteins is required for virus infection and virus-induced cell fusion. It has also been suggested that cleavage of gp120 at the immunodominant V3 loop region is required for virus-to-cell and cell-to-cell fusion. In this investigation we have studied the proteolytic processing of the HIV-1 Env in cells of various origins (human, monkey, and mouse) infected with a vaccinia virus recombinant expressing the entire gp160 protein (VV-env-1). We have observed that in murine Ltk(-) cells, in addition to the proteolytic cleavage of gp160 at the gp120/gp41 site, there is also extensive intracellular proteolytic processing of gp160 at the V3 loop and at a novel site located at the C terminus of gp41. Similar proteolytic processing of the Env precursor was observed after treatment of extracts of VV-env-1-infected monkey cells with thrombin, a trypsin-like protease that has been shown to cleave the gp120 at the V3 loop. Our findings suggest that murine Ltk(-) cells could be a good model system for structural studies of Env with different HIV isolates and in searches for proteinase inhibitors that could prevent HIV-1 infection of susceptible cells by blocking proteolysis of Env.
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PMID:Enhanced proteolytic processing of the human immunodeficiency virus type 1 envelope protein in murine Ltk(-) cells. 773 99

A processing protease for the human immunodeficiency virus type I (HIV-I) envelope glycoprotein gp160 precursor has been purified to homogeneity from the post-nuclear membrane fraction of a human T4+ lymphocyte clone. Most of the processing activity was found to be present in the fractions of endoplasmic reticulum and Golgi apparatus of the cells. The purified enzyme has a monomeric structure with a molecular mass of 26 +/- 3 kDa, as judged by gel-permeation liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions. The purified enzyme converted gp160 to gp120 and gp41, showing a pH optimum of 6.5-7.0. Direct amino acid sequencing of the amino terminus of the product gp41 revealed that the cleavage site of gp160 was between Arg511 and Ala512. The enzyme activity was inhibited by trypsin-type protease inhibitors, but was not affected by CaCl2, MgCl2 or chelating agents. The properties of the purified enzyme are clearly distinct from those of processing proteases reported previously. Although the significance of the enzyme in vivo is not currently certain, judging from its cleavage specificity and subcellular localization, this endopeptidase appears to be a processing enzyme for the human immunodeficiency virus type I gp160 precursor protein in human T cells.
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PMID:Processing protease for gp160 human immunodeficiency virus type I envelope glycoprotein precursor in human T4+ lymphocytes. Purification and characterization. 809 9

The serum level of placental leucine aminopeptidase (P-LAP) increases during pregnancy. P-LAP degrades several peptide hormones such as oxytocin and vasopresin, suggesting a role in maintaining homeostasis during pregnancy. In the study reported here, we have isolated a cDNA clone with 4084 base pairs encoding P-LAP from a human placental cDNA library. The amino acid sequence deduced from the cDNA contained all of the sequences of the peptide fragments obtained by digestion of the purified protein with trypsin. The predicted P-LAP contains the HEXXH consensus sequence of zinc metallopeptidases, indicating that the enzyme belongs to this family, which includes aminopeptidase N and aminopeptidase A. The deduced sequence also contains a hydrophobic region near the N terminus, suggesting that the enzyme is a type II integral membrane protein. Northern blot analysis revealed that P-LAP was expressed in several tissues, some of which expressed two forms of mRNAs. These results suggest that the enzyme is synthesized as an integral membrane protein and is released into blood under some physiological conditions.
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PMID:Human placental leucine aminopeptidase/oxytocinase. A new member of type II membrane-spanning zinc metallopeptidase family. 855 Jun 19

An alpha-factor leader/insulin precursor fusion protein was produced in Saccharomyces cerevisiae and metabolically labeled in order to analyse the efficiency of maturation and secretion. A substantial fraction of the secreted material was found in a hyperglycosylated unprocessed form, indicating incomplete Kex2p endopeptidase maturation. Introduction of a spacer peptide (EAEAEAK) after the dibasic Kex2p site, creating a N-terminal extension of the insulin precursor, greatly increased the Kex2p catalytic efficiency and the fermentation yield of insulin precursor. The N-terminal extension features a Lys to allow subsequent proteolytic removal by trypsin or the Achromobacter lyticus Lys-specific protease. Dipeptidyl aminopeptidase A (DPAPA) activity removing Glu-Ala dipeptides from the extension was inhibited by adding a Glu N-terminally to the extension. Unexpectedly, this modified N-terminal extension (EEAEAEAK) was partially cleaved after the Lys during fermentation. This monobasic proteolytic activity was demonstrated to be associated with Yap3p. Yap3p cleavage could be prevented by insertion of a Pro before the Lys (EEAEAEAPK).
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PMID:A removable spacer peptide in an alpha-factor-leader/insulin precursor fusion protein improves processing and concomitant yield of the insulin precursor in Saccharomyces cerevisiae. 862 Oct 69

Aminopeptidase A (glutamyl aminopeptidase; EC 3.4.11.7) has been cloned from porcine brain and kidney cortex cDNA libraries and the complete primary sequence of the enzyme deduced. This predicts a type II integral membrane protein of 942 amino acids with 14 potential N-linked glycosylation sites and a His-Glu-Xaa-Xaa-His zinc binding motif. Aminopeptidase A was purified from porcine kidney cortex by a combination of anion exchange and hydrophobic interaction chromatographies following its release from the membrane by trypsin. The purified protein migrated as three major polypeptides on SDS-polyacrylamide gel electrophoresis of M(r) 147,000, 107,000, and 45,000. N-Terminal sequencing revealed that both the Mr 147,000 and 107,000 polypeptides had the same N-terminal sequence resulting from cleavage of aminopeptidase A by trypsin at the Lys-42-Asp-43 bond just outside the membrane-spanning hydrophobic region. Immunoelectrophoretic blot analysis following electrophoresis under nonreducing conditions revealed that the trypsin-cleaved form of the enzyme no longer migrated as a disulfide-linked dimer, placing the interchain disulfide link N-terminal to Lys-42. N-Terminal sequencing of the M(r) 45,000 polypeptide in the purified preparation of aminopeptidase A revealed that it resulted from cleavage at the Asn-602-Gly-603 bond by an endogenous protease. This posttranslational proteolytic cleavage occurred in porcine kidney cortex microvillar membranes but not in porcine intestinal microvillar membranes. Incubation of purified porcine kidney aminopeptidase N (membrane alanyl aminopeptidase; EC 3.4.11.2) with trypsin resulted in a similar fragmentation pattern to that observed in aminopeptidase A, suggesting that these and other members of the type II membrane-spanning zinc aminopeptidase family may have two distinct domains: an N-terminal domain, containing the zinc binding site and residues identified as being involved in catalysis, and a C-terminal domain of unknown function, that are separated by a protease-susceptible region.
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PMID:Proteolytic fragmentation reveals the oligomeric and domain structure of porcine aminopeptidase A. 906 31

Maturation of the fetal gastrointestinal tract (GIT) is influenced by both luminal stimuli (e.g. swallowed fluid) and hormonal factors (e.g. endogenous cortisol release). The aims of the present study were 1) to investigate GIT growth and maturation during the last 20% of gestation in pigs (term = 114 +/- 2 d), and 2) to investigate the effect of esophageal ligation, to prevent fetal swallowing, at 80% to 91% gestation. In normal fetuses, marked increases occurred during late gestation in body weight (+95%), relative intestinal weight (+79%, g kg(-1) body weight), activity of some digestive enzymes (1.5- to 10-fold), and absorption of glucose and intact proteins (3- to 6-fold). Fetuses with ligated esophagi had lowered body weight (-20%), reduced intestinal weight (-43%), aminopeptidase A activity (-24%), and glucose absorption (-27%), while lactase, sucrase, and dipeptidylpeptidase IV activities were increased (+40-50%), compared with sham-operated fetuses (all p < 0.05). Other parameters of GIT function remained unchanged by esophageal obstruction (absorption of amino acids and immunoglobulin, activity of chymosin, amylase, trypsin, chymotrypsin, maltase, aminopeptidase N -- all expressed per gram GIT tissue). Ligated fetuses had elevated cortisol levels, which is known to stimulate fetal GIT maturation. We conclude that the rapid development of GIT function in late gestation is diminished by esophageal obstruction, mainly due to slower GIT growth and not inhibition of normal functional development of enterocytes.
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PMID:Prenatal development of gastrointestinal function in the pig and the effects of fetal esophageal obstruction. 1219 78


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