Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neutrophils and mononuclear cells have been associated with the lower respiratory tract inflammation observed in both acute and chronic bronchitis. In order to transit into and remain within the airways, neutrophils and mononuclear cells would likely need to adhere to bronchial epithelium. To test this hypothesis, bovine bronchial epithelial cells (BBECs) were isolated and cultured on a round coverslip. After 7 to 10 days, 51Cr-labeled neutrophils and mononuclear cells were evaluated for their capacity to adhere to the BBEC monolayer. Both neutrophils and mononuclear cells readily bound to the BBEC monolayer (10.8 +/- 1.2% bound neutrophils; 40.5 +/- 2.8% bound mononuclear cells). Stimulation of the neutrophils and mononuclear cells with phorbol 12-myristate 13-acetate (PMA) increased the adherence (45.8 +/- 10.6% bound neutrophils, P less than 0.01 compared with unstimulated cells; 58.7 +/- 6.2% bound mononuclear cells, P less than 0.01 compared with unstimulated cells). Importantly, stimulating the BBEC monolayer with PMA, bacterial lipopolysaccharide, or a cigarette smoke extract for 4 to 72 h also increased the adherence of both cell types (P less than 0.01, all comparisons at 24 h). The adherence was not decreased by exposure of either the BBEC monolayer, the neutrophils, or the mononuclear cells to cycloheximide or to the anti-CD11/CD18 monoclonal antibody 60.3 (P greater than 0.05). However, exposure of the BBEC monolayer to trypsin before addition of the neutrophils significantly decreased adherence (P less than 0.05). Because neutrophils and mononuclear cells are thought to mediate cell cytotoxicity by adhering to the target cells, BBECs were labeled with 51Cr, and 51Cr release was measured as an index of cytotoxicity. There was a modest increase in 51Cr release by the addition of unstimulated neutrophils and mononuclear cells, and culturing the BBEC monolayer with PMA before the addition of the neutrophils or mononuclear cells resulted in a further modest enhancement of 51Cr release (P less than 0.05). Similar results were obtained using lactate dehydrogenase release as a measure of cytotoxicity. These results demonstrate that inflammatory cells can adhere to BBECs and may be capable of mediating cytotoxicity and adherence and cytotoxicity can be increased by stimulating BBECs.
Am J Respir Cell Mol Biol 1992 Jul
PMID:Modulation of neutrophil and mononuclear cell adherence to bronchial epithelial cells. 162 34

We describe some properties on an Mr 30,000 thermolabile and trypsin-sensitive protein that activates phospholipase A2 (PLA2) and which was isolated from nervous tissue of the marine mollusk, Aplysia californica. A similar protein is present in rat cerebral cortex. This protein was partially purified from crude homogenates of nervous tissue by ion exchange chromatography on DEAE-Sephadex followed by size-exclusion high performance liquid chromatography (HPLC). It is loosely associated with membrane fractions, and is extracted by 0.05% Tween 20. Although similar in size to several previously described PLA2-stimulating proteins from non-neural mammalian cells and tissues, it differs from them in some aspects of biological activity. The protein promotes the release of eicosanoids from the membranes of intact Aplysia neurons prelabeled with [3H]arachidonic acid and appears to be an in vitro substrate for protein kinase C (PKC). PLA2-stimulating activity is greatly enhanced after exposing isolated ganglia to phorbol dibutyrate (PDBu) and is reduced by treatment with immobilized E. coli alkaline phosphatase. These observations suggest that phosphorylation of this stimulatory protein by PKC regulates PLA2 in neurons.
Brain Res Mol Brain Res 1991 Mar
PMID:A phospholipase A2-stimulating protein regulated by protein kinase C in Aplysia neurons. 164 37

Active diphtheria toxin consists of two disulphide-linked fragments, termed A and B. Fragment B, which contains an internal disulphide bridge, facilitates translocation of the enzymatically active fragment A to the cytosol of eukaryotic cells. In this process cation-selective channels are formed. An in vitro translated full-length mutant lacking the internal disulphide bridge (A-58**) was functionally indistinguishable from its disulphide-containing counterpart (A-58) with respect to trypsin sensitivity, receptor binding, A-fragment translocation, and channel formation. In contrast, the B fragment of A-58** (B-36**) was slightly less trypsin resistant than the S-S-containing B fragment, B-36, and was approximately 300-fold less efficient than B-36 in permeabilizing cells. When first dialysed and then reconstituted with A fragment, B fragment without disulphide bridge yielded a less-active toxin than did wild-type B fragment. We conclude that the disulphide bridge in fragment B is not necessary for toxicity, as earlier believed, and that channel formation may play a role in membrane translocation.
Mol Microbiol 1991 Mar
PMID:Elimination of the disulphide bridge in fragment B of diphtheria toxin: effect on membrane insertion, channel formation, and ATP binding. 164 74

In reconstituted rabbit skeletal muscle (Ca2+ + Mg2+)-ATPase proteoliposomes, Ca(2+)-uptake is decreased by more than 90% with T2 cleavage (Arg-198). However, no difference in the ATP dependence of hydrolysis activity is seen between SR and trypsin-treated SR. A large decrease in E-P formation and hydrolysis activity of the enzyme appear only at T3 cleavage, which represents the cleavage of A1 fragment to A1a + A1b forms. The disappearance of hydrolysis activity due to digestion is prior to the disappearance of E-P formation. No significant difference is found in the passive Ca2+ efflux between control SR and tryptically digested SR in the absence of Mg2+ + ruthenium red or in the presence of ATP. However, the passive Ca2+ efflux rate for tryptically digested SR is much larger than control SR in the presence of Mg2+ + ruthenium red. These results show that the Ca2+ channel cannot be closed after trypsin digestion of SR membranes by the presence of the Ca2+ channel inhibitors, Mg2+ and ruthenium red. In the reconstituted proteoliposomes, the Ca2+ efflux rates are the same regardless of digestion (T2); also, efflux is not affected by the presence or absence of Mg2+ + ruthenium red. These results indicate that T2 cleavage causes 'uncoupling' of the 'Ca(2+)-pump' from ATP hydrolytic activity. A theoretical model is developed in order to fit the extent of tryptic digestion of the A fragment of the (Ca2+ + Mg2+)-ATPase polypeptide with the loss of Ca(2+)-transport. Fits of the theoretical equations to the data are consistent with that Ca(2+)-transport system appears to require a dimer of the polypeptide (Ca2+ + Mg2+)-ATPase.
Mol Cell Biochem 1991 May 15
PMID:Uncoupling of Ca2+ transport from ATP hydrolysis activity of sarcoplasmic reticulum (Ca2+ + Mg2+)-ATPase. 164 82

We have reported earlier that cholinephosphotransferase (EC 2.7.8.2) is present in both mitochondria and microsomes of fetal guinea pig lung. This study was designed to compare the properties of mitochondrial and microsomal cholinephosphotransferase in fetal guinea pig lung. Various parameters, such as substrate specificity, Km values, sensitivity to N-ethylmaleimide, dithiothreitol and trypsin were measured. Both showed significant preference for unsaturated diacylglycerols over saturated diacylglycerols. Data on Km and Vmax indicate that the affinity of this enzyme for different diacylglycerols varies between the two forms. The ID50 values for N-ethylmaleimide were 20 mM and 12.5 mM for the mitochondrial and microsomal form of the enzyme, respectively. Dithiothreitol showed an inhibitory effect on both; however, the mitochondrial form was inhibited less than the microsomal form. The effects of N-ethylmaleimide and dithiothreitol on both forms of enzyme indicated that the microsomal cholinephosphotransferase requires a higher concentration of -SH for its activity than the mitochondrial enzyme does. The enzyme was inhibited by trypsin in both mitochondria and microsome under isotonic condition suggesting that this enzyme is on the outside of the membrane in both endoplasmic reticulum and mitochondria.
Mol Cell Biochem 1991 Mar 13
PMID:Study of properties of cholinephosphotransferase from fetal guinea pig lung mitochondria and microsomes. 165 Apr 26

Fast inactivation of Na channels in neonatal cardiac cells was removed by the action of proteolytic enzymes trypsin or papain. Two stages were apparent in the time course of this process. During the first one, both number of channel reopenings and the mean open time increased markedly even though fast inactivation remained complete. The second stage was manifested by the disappearance of all signs of fast inactivation without further noticeable changes in channel mean open time. At the same time the nonrandom clustering of blank response (response without channel openings) trials became prominent. The data obtained support the interpretation of two separate fast inactivation states in cardiac Na channels as suggested in our previous papers (Zilberter et al. (1989) in Neuromuscular Junction (Sellin, L.C., Libelius, R. and Thesleff, S., eds.), pp. 43-50, Elsevier, Amsterdam, and Zilberter et al. (1991) J. Mol. Cell. Cardiol. 23, (Suppl.) 61-72).
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PMID:Existence of two fast inactivation states in cardiac Na channels confirmed by two-stage action of proteolytic enzymes. 165 6

The MET proto-oncogene encodes a 190-kDa disulfide-linked heterodimeric receptor (p190 alpha beta) whose tyrosine kinase activity is triggered by the hepatocyte growth factor. The mature receptor is made of two subunits: an alpha chain of 50 kDa and a beta chain of 145 kDa, arising from proteolytic cleavage of a single-chain precursor of 170 kDa (pr170). In a colon carcinoma cell line (LoVo), the precursor is not cleaved and the Met protein is exposed at the cell surface as a single-chain polypeptide of 190 kDa (p190NC). The expression of the uncleaved Met protein is due to defective posttranslational processing, since in this cell line (i) the proteolytic cleavage site Lys-303-Arg-Lys-Lys-Arg-Ser-308 is present in the precursor, (ii) p190NC is sensitive to mild trypsin digestion of the cell surface, generating alpha and beta chains of the correct size, and (iii) the 205-kDa insulin receptor precursor is not cleaved as well. p190NC is a functional tyrosine kinase in vitro and is activated in vivo, as shown by constitutive autophosphorylation on tyrosine. The MET gene is neither amplified nor rearranged in LoVo cells. Overlapping cDNA clones selected from a library derived from LoVo mRNA were sequenced. No mutations were present in the MET-coding region. These data indicate that the tyrosine kinase encoded by the MET proto-oncogene can be activated as a consequence of a posttranslational defect.
Mol Cell Biol 1991 Dec
PMID:Defective posttranslational processing activates the tyrosine kinase encoded by the MET proto-oncogene (hepatocyte growth factor receptor). 165 24

Cyclic AMP mediates the hormonal stimulation of a number of eukaryotic genes by directing the protein kinase A (PK-A)-dependent phosphorylation of transcription factor CREB. We have previously determined that although phosphorylation at Ser-133 is critical for induction, this site does not appear to participate directly in transactivation. To test the hypothesis that CREB ultimately activates transcription through domains that are distinct from the PK-A site, we constructed a series of CREB mutants and evaluated them by transient assays in F9 teratocarcinoma cells. Remarkably, a glutamine-rich region near the N terminus appeared to be important for PK-A-mediated induction of CREB since removal of this domain caused a marked reduction in CREB activity. A second region consisting of a short acidic motif (DLSSD) C terminal to the PK-A site also appeared to synergize with the phosphorylation motif to permit transcriptional activation. Biochemical experiments with purified recombinant CREB protein further demonstrate that the transactivation domain is more sensitive to trypsin digestion than are the DNA-binding and dimerization domains, suggesting that the activator region may be structured to permit interactions with other proteins in the RNA polymerase II complex.
Mol Cell Biol 1991 Mar
PMID:Characterization of motifs which are critical for activity of the cyclic AMP-responsive transcription factor CREB. 167 8

Several lines of evidence suggest a possible role for mast cell proteases in modulating the biologic effects of neuropeptides. To explore the potential of such interactions in human airway, we examined the activity of human tryptase, the major secretory protease of human lung mast cells, against several neuropeptides with proposed regulatory functions in human airway. Using highly purified tryptase obtained from extracts of human lung, we determined the sites and rats of hydrolysis of vasoactive intestinal peptide (VIP), peptide histidine-methionine (PHM), calcitonin gene-related peptide (CGRP), and the tachykinins substance P (SP), neurokinin A (NKA), and neurokinin B (NKB). Tryptase hydrolyzes VIP rapidly at several sites (Arg12, Arg14, Lys20, and Lys21) with an overall kcat/Km of 1.5 x 10(5) M-1 s-1 and hydrolyzes PHM primarily at a single site (Lys20) with a kcat/Km of 1.9 x 10(4) M-1 s-1. Tryptase also rapidly hydrolyzes CGRP at two sites (Arg18 and Lys24) with a kcat/Km of 2.7 x 10(5) M-1 s-1. The tachykinins are not hydrolyzed by tryptase. These observations raise the possibility that tryptase-mediated degradation of the bronchodilators VIP and PHM combined with exaggerated mast cell release of tryptase may contribute to the increase in bronchial responsiveness and the decrease in immunoreactive VIP in airway nerves associated with asthma. The favorable rates of hydrolysis of CGRP suggest that tryptase may also terminate the effects of CGRP on bronchial and vascular smooth muscle tone and permeability.
Am J Respir Cell Mol Biol 1990 Jul
PMID:Degradation of airway neuropeptides by human lung tryptase. 169 72

The TraT protein is a surface-exposed lipoprotein, specified by plasmids of the IncF group, that mediates serum resistance and surface exclusion. The structure and function of the TraT protein determined by plasmid R6-5 was probed by genetic insertion of a foreign antigenic determinant, the C3 epitope of polio virus, at residues 61, 125, 180, 200 or 216 of the protein. The chimaeric proteins were transported to the outer membrane and, in three cases, immunoassays with an anti-C3 monoclonal antibody indicated that the C3 epitope was exposed on the cell surface. Three of the hybrids, with insertions at residues 125, 180 and 200, assembled into the trypsin-resistant oligomeric form characteristic of the wild-type protein, which suggested that these regions are not involved in TraT subunit:subunit interactions. Additionally, the hybrid protein carrying the C3 epitope at position 180 functioned in a genetic suppression assay and retained partial surface-exclusion activity. Thus, its localization, folding and organization does not appear to be grossly altered from that of the wild-type protein. Applications of the protein for the transport of foreign antigenic determinants to the cell surface are discussed.
Mol Microbiol 1990 Aug
PMID:The TraT lipoprotein as a vehicle for the transport of foreign antigenic determinants to the cell surface of Escherichia coli K12: structure-function relationships in the TraT protein. 170 95


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