Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oviduct membranes from chicks treated with diethylstilbestrol have a fully induced level of an enzyme that transfers mannose from GDP-Man to form mannosylphosphoryldolichol (Lucas, J.J. and Levin, E. (1977) J. Biol. Chem.252, 4330--4336). Withdrawal of diethylstilbestrol for 5 days causes a decrease in oviduct weight, lysozyme, and 60% of the mannosyltransferase activity. Chicks withdrawn from treatment for 10 days followed by secondary stimulation with diethylstilbestrol exhibit a more rapid increase in the mannosyltransferase activity than chicks that have not been previously treated with diethylstilbestrol. Further experiments indicate that the decrease in mannosylphosphoryldolichol synthesis after hormonal withdrawal may be the result of decreased levels of endogenous dolichyphosphate in the membrane preparations.
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PMID:Effect of progesterone, estrogen withdrawal and secondary estrogen treatment of mannosylphosphoryldolichol synthesis in chick oviduct membranes. 57 62

Activation of neutrophils was recently reported to be accompanied by large changes in their Cl- content [J. B. Myers, H. F. Cantiello, J. H. Schwartz, and A. I. Tauber. Am. J. Physiol. 259 (Cell Physiol. 28): C531-C540, 1990]. The significance of these ionic changes to the immune response has not been studied. To evaluate the role of intracellular [Cl-], the anionic composition of the cytosol was varied in human neutrophils permeabilized by electroporation or by treatment with streptolysin O. In Cl(-)-rich media, permeabilized but otherwise untreated cells remained quiescent, resembling unstimulated intact cells. In contrast, suspension of permeabilized cells in Cl(-)-depleted media elicited protein phosphorylation, actin polymerization, secretion of lysozyme, and a respiratory burst. The latter was demonstrated by several criteria to be mediated by the NADPH oxidase. The responses observed in Cl(-)-depleted media were insensitive to pretreatment of the cells with pertussis toxin but were inhibited by addition of GDP or by omission of ATP. The data suggest that an early event in signal transduction, common to several effectors, is sensitive to the ionic composition of the cytosol. This component, possibly a GTP-binding protein, may be affected by the anion concentration changes reported to occur during physiological stimulation of neutrophils.
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PMID:Activation of permeabilized neutrophils: role of anions. 163 84

We studied the effect of adenosine nucleotides on several aspects of the functional activation of human peripheral blood polymorphonuclear leukocytes (PMN). Radiolabeled ATP bound to PMN in a manner suggesting the existence of specific binding sites because: 1) binding was reversed (92 +/- 6%) by 100-fold excess concentrations of unlabeled ATP but minimally by either ADP (43 +/- 12%) or GTP (37 +/- 8%); and 2) binding saturation was achieved (i.e., specific binding did not increase) above 250 microM ATP. Binding studies revealed that significant ATP hydrolysis occurred, even at low temperatures and in the presence of phosphatase inhibitors. Adenosine nucleotides activated signal transduction mechanisms in PMN because: 1) 1 to 100 microM ATP and 5'-adenylylimidodiphosphate (AMP-PNP) stimulated increased production of 1,2-diacylglycerols; 2) ATP (0.5 to 500 microM) and ADP (0.1 to 10 mM) induced increased insoluble protein kinase (PKC) activity in a dose-dependent manner when used at concentrations greater than 50 microM; 3) ATP (greater than or equal to 50 microM) induced a shift in the solubility of phorbol receptors from mostly soluble (89% in untreated cells) to mostly insoluble (68%), whereas ADP, GTP, and GDP were effective at higher concentrations; and 4) greater than or equal to 50 microM ATP stimulated increased phosphorylation of endogenous PMN proteins. AMP-PNP induced PKC activity and phosphoprotein changes that were qualitatively similar to those observed when PMN were treated with ATP, suggesting that extracellular ATP hydrolysis is not required for signal transduction to activate PKC. Functionally, ATP stimulated the secretion of specific (but not azurophil) granules because vitamin B12-binding protein and low levels of lysozyme, but not beta-glucuronidase, were released; qualitatively similar results were obtained by using AMP-PNP. These results suggest that certain adenosine nucleotides employed at physiologically relevant concentrations stimulate increased 1,2-diacylglycerol production, PKC activity, granule secretion, and endogenous phosphoprotein formation in a manner that is independent of extracellular ATP hydrolysis.
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PMID:Extracellular adenosine nucleotides stimulate protein kinase C activity and human neutrophil activation. 215 72

Human neutrophils can be permeabilized with the cholesterol complexing agent digitonin and then induced to secrete lysosomal constituents by increases in free Ca2+ alone. In order of increasing requirements for Ca2+, vitamin B-12 binding protein, lysozyme and beta-glucuronidase were released. A variety of guanine nucleotides were examined with respect to their abilities to modulate this response. GTP, along with its analogues 5'-guanylylimidodiphosphate (Gpp[NH]p) and guanosine-5'-O-[3-thio]-triphosphate (GTP[gamma S]) decreased the Ca2+ requirements for secretion of all three granule constituents by one third to one order of magnitude. This synergy was dependent upon the concentration of guanine nucleotides employed. The effects of Gpp[NH]p could be blocked with the inactive derivative GDP[beta-S]. The active guanine nucleotides, particularly GTP, served as stimuli in their own right. At high concentrations of Ca2+ and GTP, degranulation was strikingly inhibited; inhibition was also achieved with high concentrations of guanylyl[beta, gamma-methylene]diphosphate (Gpp[CH2]p). Both GDP and GMP were without any effect. When neutrophils were pretreated with pertussis toxin, granule discharge induced by fMet-Leu-Phe was almost completely blocked, as reported by others. If the neutrophils pretreated with pertussis toxin were then permeabilized with digitonin, the synergy between Ca2+ and the stimulatory guanine nucleotides was maintained. These data suggest the involvement of G-proteins in secretion induced by Ca2+; however, this response either uses a different G-protein or a different pool of G-proteins from those responses triggered by fMet-Leu-Phe.
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PMID:Guanine nucleotides reduce the free calcium requirement for secretion of granule constituents from permeabilized human neutrophils. 353 3