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)

A new serine protease was encoded by a clone isolated from a murine cytotoxic T-lymphocyte complementary DNA library by an RNA-hybridization competition protocol. Complementary transcripts were detected in cytotoxic T lymphocytes, spleen cells from nude mice, a rat natural killer cell leukemia, and in two of eight T-helper clones (both cytotoxic), but not in normal mouse kidney, liver, spleen, or thymus, nor in several tested T- and B-cell tumors. T-cell activation with concanavalin A plus interleukin-2 induced spleen cells to express this gene with kinetics correlating with the acquisition of cytolytic capacity. The nucleotide sequence of this gene encoded an amino acid sequence of approximately 25,700 daltons, with 25 to 35 percent identity to members of the serine protease family. The active site "charge-relay" residues (His57, Asp102, and Ser195 of the chymotrypsin numbering system) are conserved, as well as the trypsin-specific Asp (position 189 in trypsin). A Southern blot analysis indicated that this gene is conserved in humans, mouse, and chicken. This serine protease may have a role in lymphocyte lysis and a "lytic cascade."
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PMID:Cloning of a cDNA for a T cell-specific serine protease from a cytotoxic T lymphocyte. 242 55

A cDNA clone encoding a human T cell- and natural killer cell-specific serine protease was obtained by screening a phage lambda gt10 cDNA library from phytohemagglutinin-stimulated human peripheral blood lymphocytes with the mouse Hanukah factor cDNA clone. In an RNA blot-hybridization analysis, this human Hanukah factor cDNA hybridized with a 1.3-kilobase band in allogeneic-stimulated cytotoxic T cells and the Jurkat cell line, but this transcript was not detectable in normal muscle, liver, tonsil, or thymus. By dot-blot hybridization, this cDNA hybridized with RNA from three cytolytic T-cell clones and three noncytolytic T-cell clones grown in vitro as well as with purified CD16+ natural killer cells and CD3+, CD16- T-cell large granular lymphocytes from peripheral blood lymphocytes (CD = cluster designation). The nucleotide sequence of this cDNA clone encodes a predicted serine protease of 262 amino acids. The predicted protein has a 22-amino acid presegment, a 6-amino acid prosegment, and an active enzyme of 234 amino acids with a calculated unglycosylated molecular weight of 25,820. The active enzyme is 71% and 77% similar to the mouse sequence at the amino acid and DNA level, respectively. The human and mouse sequences conserve the active site residues of serine proteases--the trypsin-specific Asp-189 and all 10 cysteine residues. The gene for the human Hanukah factor serine protease is located on human chromosome 5. We propose that this trypsin-like serine protease may function as a common component necessary for lysis of target cells by cytotoxic T lymphocytes and natural killer cells.
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PMID:Cloning and chromosomal assignment of a human cDNA encoding a T cell- and natural killer cell-specific trypsin-like serine protease. 325 74

The terminal killer cell-independent lysis (KCIL) stage of the human natural killer (NK) lethal hit is blocked by the protease enzymes trypsin (T), chymotrypsin (CT), and papain (P). The present studies analyze the mechanism of inhibition of KCIL by these enzymes. The pretreatment of effector PBL with T or CT but not P effectively reduced the ability of these cells to mediate NK lysis. This was due at least in part to a reduced ability of the treated NK cells to bind the NK target K562. Pretreatment of K562 cells with T, CT, or P also abolished their ability to serve as targets due to reduced binding ability. These same enzyme-pretreated target cells, however, were unaffected in their ability to bind a natural killer cell-derived cytolytic factor (NKCF) molecule(s), as determined by direct NKCF absorption studies or by their ability to cold target compete for the binding of NKCF to another NKCF-sensitive cell, the L929 fibroblast, thereby indicating that the K562 "target antigen" and the NKCF-receptor are independently expressed structures. Furthermore, NKCF activity, as measured by its ability to kill either K562 or L929 cells, was sensitive to T and CT but resistant to P. These studies indicate that various proteases inhibit NK-KCIL by different mechanisms and suggest that the lethal hit is a complex process. The ability of P to inhibit KCIL but not affect NKCF activity or the target cell NKCF receptor implies that additional NK cell-derived materials may be required in the lethal hit during direct NK cell-mediated cytotoxicity. A model depicting a hypothetical molecular mechanism for human NK cytolysis is presented and discussed.
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PMID:Studies on the mechanism of the human natural killer cell lethal hit: analysis of the mechanism of protease inhibition of the lethal hit. 635 52

These studies analyze the effects of various enzymes on the terminal, killer cell-independent (KCIL) stages of the human natural killer (NK) cytolytic mechanism. The addition of trypsin (T), chymotrypsin (CT), or papain (P) to standard NK reaction mixtures (PBL or LGL and K562 cells) completely ablated cytolytic activity, whereas collagenase was ineffective. Inhibition by T was reversed by preincubation with soybean trypsin inhibitor (SBTI) or fetal calf serum, indicating that the inhibition was indeed due to T. Kinetic analysis with the Ca++ pulse experiment indicated that T, CT, and P inhibited lysis well beyond the Ca++-dependent (EDTA-sensitive) stages and essentially stopped further 51Cr release at the time of addition. This observation was confirmed by the ability of T, CT, and P to block lysis during KCIL of programmed K562 targets that were detached from NK cells by EDTA and were suspended in dextran-containing media. The lysis of K562 cells by natural killer cell-derived cytotoxic factors (NKCF) was also blocked by T and CT but not by P. Inhibition of NKCF activity by T could be reversed by SBTI or fetal calf serum. The ability of T, CT, or P to inhibit the lysis of "programmed" K562 targets during KCIL indicates that the NK lethal hit is an active process mediated by protease-sensitive structures, possibly NKCF, delivered to the target cell by the NK cell during the Ca++-dependent programming steps.
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PMID:Studies on the mechanism of the human natural killer cell lethal hit: evidence for transfer of protease-sensitive structures requisite for target cell lysis. 635 53

Human natural cell-mediated cytotoxicity is inhibited by macromolecular protease inhibitors. Human plasma alpha 1 antiproteases are more effective than the plant antiproteases lima bean trypsin inhibitor and soybean trypsin inhibitor for reduction of cytotoxicity to the "slow" targets T24 human bladder carcinoma and NKI-1 melanoma. This inhibition of natural cytotoxicity is more readily demonstrable in serum-free medium containing crystalline bovine serum albumin than in medium containing fetal calf serum. Although electrophoretically homogeneous plasma alpha 1 antitrypsin inhibits natural cytotoxicity, partially purified alpha 1 antitrypsin preparations that contain several apha 1 proteins are more inhibitory at equivalent trypsin inhibitory capacities. Partially purified alpha 1 antichymotrypsin with no antitrypsin activity is an extremely potent inhibitor. Thus, it seems likely that several of the plasma antiproteases, including alpha 1 antitrypsin and alpha 1 antichymotrypsin, are capable of influencing natural cytotoxicity. These data indicate that serine-dependent proteases hae a critical role in triggering and/or effecting cell-mediated cytolysis. Furthermore, since alpha 1 antichymotrypsin and alpha 1 antitrypsin are acute phase proteins, the increase in plasma concentration or turnover rates of the proteins could influence natural killer cell activity in vivo.
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PMID:Inhibition of human natural cytotoxicity by macromolecular antiproteases. 697 Jul 80

Granzymes are a family of granule serine proteases found specifically in the cytotoxic granules of cytotoxic T lymphocytes and natural killer cells. Granzymes have features that are strongly conserved including: consensus sequences at their N-termini and around the three catalytic residues, activation from zymogenic forms, and conserved disulphide bridges. However, there is good genetic evidence to suggest that three distinct subfamilies of granzymes have coevolved. These subfamilies are most strikingly depicted by their distinct chromosomal loci and gene organization, dividing the granzyme family into subfamilies of the following: tryptases (human chromosome 5); chymotrypsin-like proteases (human chromosome 14); and a Metase amongst a cluster of elastase-like proteases (human chromosome 19). Modeling and mutational analysis has revealed that each subfamily of granzymes displays special sequence and structural features and a proteolytic specificity determined by subtle modifications to substrate binding pocket residues. It now remains of great interest to determine whether these subfamilies also possess distinct biological functions. Granzyme B has been shown to play an important role in lymphocyte-mediated target cell apoptosis and the tryptase, granzyme A, has been demonstrated to regulate the clearance of some pox virus infections. The future creation of other granzyme gene knockout mice should elucidate whether other chymotrypsin-like granzymes (C-H) also contribute to target cell apoptosis and whether the third subfamily member, natural killer cell-specific Metase, has a distinct biological function.
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PMID:Granzymes: a variety of serine protease specificities encoded by genetically distinct subfamilies. 892 45

We have examined the ability of several serine proteases (granzymes) isolated from the granules of the rat natural killer cell line, RNK, to generate antigenic peptides of ovalbumin (Ova) that are capable of being recognized by Ova-specific CD8+ T cells. The mouse MHC class I-restricted cytotoxic T-cell clone, GX-1, which recognizes a trypsinized fragment of Ova in the context of H-2b, was able to lyse EL4 (H-2b) target cells in the presence of Ova and the granzymes but not in the presence of Ova or granzymes alone. Similar results were obtained using the murine Ova-specific CD8+ T cell hybridomas, RF33.70 and CD8OVA. In all cases, the T cells' responses were MHC class I-restricted as Ova:granzyme mixtures failed to mediate the lysis of the MHC-disparate target cell, P815 (H-2d). The purified rat granzyme preparations contained three distinct enzymatic specificities: asp-ase met-ase, and tryptase. Aprotinin, a protease inhibitor that only inhibits tryptase activity in vitro, completely abolished the CD8+ T-cell responses to Ova. These results, along with peptide loading studies using the RMA-S cell line, suggest that the granzyme treatment of Ova can generate the proper antigenic fragments which facilitate class I-restricted CTL responses both in vivo and in vitro. We believe that enzymes produced and released by NK or cytotoxic T cells within a tissue microenvironment may enhance the cleavage of target cell antigens as well as soluble antigens resulting in the improved uptake and processing of soluble antigens.
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PMID:Generation of antigenic peptides by lymphocyte granule serine proteases (granzymes). 896 86

Interleukin-15 (IL-15) is a potent regulator of T-, B-, and natural killer cell proliferation and displays unusually tight controls of secretion. Even though IL-15 mRNA is constitutively expressed in monocytes/macrophages and is upregulated by a variety of stimuli, evidence for IL-15 cytokine secretion is only found exceptionally, eg, conditions of pathological, chronic inflammation. This raises the possibility that monocytes express membrane-bound IL-15 rather than secrete it. The current study explores this hypothesis. We demonstrate here that biologically active IL-15 is indeed detectable in a constitutively expressed, membrane-bound form on normal human monocytes, as well as on monocytic cell lines (MONO-MAC-6, THP-1, and U937), but not on human T or B cells (MT4, M9, C5966, JURKAT, DAUDI, RAJI, and Epstein-Barr virus-immortalized B-cell clones). Furthermore, cell surface-bound IL-15 is upregulated upon interferon-gamma stimulation. Interestingly, monocyte/macrophage inhibitory cytokines such as IL-4 and IL-13 fail to downregulate both constitutive and induced cell-surface expression of IL-15. Membrane-bound IL-15 does not elute with acetate buffer or trypsin treatment, suggesting that it is an integral membrane protein and that it is not associated with the IL-15 receptor complex. Finally, membrane-bound IL-15 stimulates T lymphocytes to proliferate in vitro, indicating that it is biologically active. These findings enlist IL-15 in the fairly small family of cytokines for which the presence of a biologically active membrane-bound form has been demonstrated (eg, IL-1, tumor necrosis factor-alpha, and IL-10) and invites the speculation that most of the biological effects of IL-15 under physiological conditions are exerted by the cell surface-bound form.
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PMID:Human monocytes constitutively express membrane-bound, biologically active, and interferon-gamma-upregulated interleukin-15. 1023 6

Granzymes are granule-stored lymphocyte serine proteases that are implicated in T- and natural killer cell-mediated cytotoxic defense reactions after target cell recognition. A fifth human granzyme (granzyme 3, lymphocyte tryptase-2), renamed as granzyme K (gene name GZMK), has recently been cloned from lymphocyte tissue. For its further characterization we successfully generated catalytically active enzyme in milligram quantities per liter of Escherichia coli culture. The natural proform of granzyme K with the amino-terminal propeptide Met-Glu was expressed as inclusion bodies and converted to its active enzyme by cathepsin C after refolding of precursor molecules. Recombinant granzyme K cleaves synthetic thiobenzyl ester substrates after Lys and Arg with k(cat)/K(m) values of 3.7 x 10(4) and 4.4 x 10(4) M(-1) s(-1), respectively. Granzyme K activity was shown to be inhibited by the synthetic compounds Phe-Pro-Arg-chloromethyl ketone, phenylmethylsulfonyl fluoride, PefablocSC, and benzamidine, by the Kunitz-type inhibitor aprotinin and by human blood plasma. The plasma-derived inter-alpha-trypsin inhibitor complex, its bikunin subunit, and the second carboxyl-terminal Kunitz-type domain of bikunin were identified as genuine physiologic inhibitors with K(i) values of 64, 50, and 22 nM, respectively. Inter-alpha-trypsin inhibitor and free bikunin have the potential to neutralize extracellular granzyme K activity after T cell degranulation and may thus control unspecific damage of bystander cells at sites of inflammatory reactions.
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PMID:Generation of catalytically active granzyme K from Escherichia coli inclusion bodies and identification of efficient granzyme K inhibitors in human plasma. 1048 Sep 54

In the previous study, the proteomes of the human hepatoma cell line BEL-7404 and the normal human liver cell line L-02 were separated by high resolution two-dimensional electrophoresis (2-DE). Image analysis revealed that 99 protein spots showed quantitative and qualitative variations that were significant (P < 0.01) and reproducible. Here we report the identification results of some of these protein spots. Protein spots excised from 2-D gels were subjected to in-gel digestion with trypsin, and the resulting peptides were measured by microbore high performance liquid chromatography - ion trap - mass spectrometry (LC-IT-MS) to obtain the tandem mass (MS/MS) spectra. Twelve protein spots were identified with high confidence using SEQUEST with uninterpreted MS/MS raw data. Besides inosine-5'-monophosphate dehydrogenase 2, heat shock 27 kDa protein, calreticulin and calmodulin, whose expression was elevated in hepatoma cells, glutathione-S-transferase P was identified from hepatoma cells in which its level was 18-fold higher compared to human liver cells. Two spots were identified as the homologs of reticulocalbin for the first time in hepatoma cells and their expression increased compared to liver cells. However, tubulin beta-1 chain and natural killer cell enhancing factor B were downregulated in hepatoma cells. A tumor suppressing serpin, maspin precursor, was identified from one spot whose quantity was much higher in the normal liver cell line. More interestingly, epidermal fatty acid-binding protein (E-FABP) and fatty acid-binding protein, adipocyte-type (A-FABP), were detected in liver cells but not in hepatoma cells. The functional implication of the identified proteins was discussed.
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PMID:Identification of differentially expressed proteins between human hepatoma and normal liver cell lines by two-dimensional electrophoresis and liquid chromatography-ion trap mass spectrometry. 1100 23


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