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:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Estrogen induces a global change in the translation profile of Xenopus hepatocytes, replacing serum protein synthesis with production of the yolk protein precursor vitellogenin. This is accomplished by the coordinate destabilization of serum protein mRNAs and the transcriptional induction and subsequent stabilization of vitellogenin mRNA. Previous work identified an endonuclease activity whose appearance on polysomes correlated with the disappearance of serum protein mRNAs. This enzyme, polysomal ribonuclease 1 (PMR1), is a novel member of the peroxidase gene family. The current study examined the association of PMR1 with its mRNA targets on polysomes and mRNPs. The highest amount of polysome-bound PMR1 was observed prior to estrogen induction of mRNA decay. Its distribution on sucrose density gradients matched the absorbance profile of polysome-bound mRNA, suggesting that PMR1 forms a latent complex with mRNA. Following dissociation with EDTA the 62 kDa PMR1 sedimented with a larger complex of >670 kDa. Estrogen induces a 22-fold increase in unit enzymatic activity of polysome-bound PMR1, and a time-dependent loss of PMR1 from polysomes in a manner that mirrors the disappearance of albumin mRNA. These data suggest that the key step in the extensive estrogen-induced change in mRNA decay in Xenopus liver is activation of a latent mRNA endonuclease associated with its target mRNA.
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PMID:Polysomal ribonuclease 1 exists in a latent form on polysomes prior to estrogen activation of mRNA decay. 1122 65

Expression of aquaporin-8 mRNA has previously been shown in hepatocytes, pancreatic acinar cells, colon epithelial cells and seminiferous tubules of the testis in the rat by in situ hybridization technique. However, immunolocalization of this water channel has not yet been demonstrated. In the present study, the localization of immunoreactive aquaporin-8 and expression of the mRNA were examined in rat organs (cerebrum, cerebellum, eye, salivary gland, heart, lung, liver, pancreas, esophagus, stomach, jejunum, ileum, colon, testis, ovary, kidney, spleen and lymphnode) by immunohistochemistry using an antibody against aquaporin-8 and ribonuclease protection assay. Aquaporin-8 was distinctly immunolocalized on the apical membranes of pancreatic acinar cells and mucosal epithelium of the colon and jejunum. In the liver, the bile canalicular membrane of hepatocytes was immunostained. In the testis, immunoreactive aquaporin-8 was demonstrated on the luminal side of the seminiferous tubules. At high magnification, the peroxidase reaction products appeared on the ramified cytoplasmic membrane of Sertoli cells surrounding the residual bodies or spermatogenic cells. Specificity of the antibody was verified by Western blot analysis showing a minor approximately 28 kDa band (deduced deglycosylated form of aquaporin-8) and a major approximately 30 kDa band (glycosylated form) in these organs. The intensity of aquaporin-8 immunoreactivity was approximately comparable to that of aquaporin-8 mRNA expression in the liver, pancreas, colon, jejunum and testis. The aquaporin-8 mRNA expression in the hepatocytes was presumed to be closely associated with the structure of bile canaliculi since the message was detected in hepatocytes immediately after isolation from the liver but not in cells following cultivation for three days. The localization of immunoreactive aquaporin-8 indicated functions for this water channel in the secretion of bile and pancreatic juice, and the secretion or absorption of water in the colon and jejunum, and the maturation or liberation of spermatogenic cells in the testis.
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PMID:Immunolocalization of aquaporin-8 in rat digestive organs and testis. 1143 86

Eosinophils were separated from other types of cells in horse blood or rat peritoneal fluid by centrifugation in concentrated albumin solutions. Eosinophils did not appear to be damaged by this separation procedure. A technique was also devised for isolation of cytoplasmic granules from eosinophils, thus allowing studies on enzyme content of the granules. Granules from both horse and rat eosinophils contained a number of hydrolytic enzymes, similar in variety and in concentration to those previously found in granules of rabbit polymorphonuclear leucocytes. Eosinophil granules differed from those of the rabbit granulocyte in their high content of peroxidase and the absence of lysozyme and phagocytin. On disruption of eosinophil granules by repeated freezing and thawing in saline, cathepsin, ribonuclease, arylsulfatase and beta glucuronidase were released into solution, but phosphatases were partially and peroxidase completely bound to the insoluble granule residue. Peroxidase could be extracted from the granule residue with weak acid. Eosinophil granules thus are lysosome-like structures.
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PMID:ISOLATION OF GRANULES FROM EOSINOPHIL LEUCOCYTES AND STUDY OF THEIR ENZYME CONTENT. 1407 91

The sugar chain-binding specificity of tomato lectin (LEA) against glycoproteins was investigated qualitatively using lectin blot analysis. Glycoproteins containing tri- and tetra-antennary complex-type N-glycans were stained with LEA. Unexpectedly, glycoproteins containing high mannose-type N-glycans and a horseradish peroxidase were stained with LEA. LEA blot analysis of the glycoproteins accompanied by treatment with exoglycosidase revealed that the binding site of LEA for the complex-type N-glycans was the N-acetyllactosaminyl side chains, whereas the proximal chitobiose core appeared to be the binding site of LEA for high mannose-type N-glycans. Despite these results, the glycoproteins did not inhibit the hemagglutinating activity of LEA. Among the chitin-binding lectins compared, potato tuber lectin showed specificity similar to LEA on lectin blot analysis, while Datura stramonium lectin and wheat germ agglutinin (WGA) did not interact with glycoproteins containing high mannose-type N-glycans, except that RNase B was stained by WGA. Based on these observations, LEA blot analysis was applied to sugar chain analysis of tomato glycoproteins. The most abundant LEA-reactive glycoprotein was purified from the exocarp of ripe tomato fruits, and was identified as the tomato anionic peroxidase1 (TAP1). These results suggest that LEA interacts with glycoproteins produced by tomatoes, which participate in biological activities in tomato plants.
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PMID:Analysis of sugar chain-binding specificity of tomato lectin using lectin blot: recognition of high mannose-type N-glycans produced by plants and yeast. 1631 90

Salmonella enterica serovar Enteritidis has emerged during the last 20 years as the major causative agent of food-borne gastroenteritis in humans and as the major infectious agent on poultry farms, replacing Salmonella enterica serovar Typhimurium as the dominant pathogenic serovar. Because adhesion to gut tissues and colonization of the alimentary tract, mediated in large part by the FimH adhesins located on type 1 fimbriae, is an important stage in the pathogenesis of both serovars, the binding properties of the FimH adhesins from these two enteropathogens were compared. Salmonella Enteritidis FimH protein and the Salmonella Typhimurium low-adhesive variant of this adhesin were expressed in Escherichia coli and the recombinant proteins were analysed for their ability to bind glycoproteins carrying different oligomannosidic structures and different types of eukaryotic cells. In static binding assays (ELISA and Western blotting) both FimH proteins bound equally well to all three tested glycoproteins (RNase B, horseradish peroxidase and mannan-BSA). In addition, no differences were found in the binding specificity of the FimH proteins and intact cells of Salmonella Enteritidis and Salmonella Typhimurium to human colon carcinoma or bladder cancer cells. The presence of the same amino acid residues at positions 61 (glycine) and 118 (phenylalanine) and the similar binding properties of these two adhesins suggest that the newly described FimH protein of Salmonella Enteritidis represents the low-adhesive variant found in Salmonella Typhimurium. To study the binding specificity of Salmonella Enteritidis FimH protein further, direct kinetic analysis using surface plasmon resonance was performed. With this method it was found that Salmonella Enteritidis FimH adhesin bound with the highest K(d) value to high-mannose type N-glycans carried by RNase B; about 100 times lower K(d) values were obtained in the interactions with mannan-BSA and horseradish peroxidase.
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PMID:Functional characterization of the FimH adhesin from Salmonella enterica serovar Enteritidis. 1662 51

Protector-II (Pr-II) of the Japanese morning glory (Pharbitis nil Choisy) was inactivated by exposure to polyphenol oxidase. An unidentified protector in the same molecular weight range obtained from sunflower was also inactivated by this enzyme. Earlier speculations that protectors might be lipoprotein in nature were negated by the fact that neither lipase nor protease inactivated the protectors. The protectors were also not inactivated by incubating with alpha-amylase, DNase, or RNase. Catechol mimics Pr and is inactivated by polyphenol oxidase. The oxidation of catechol to o-quinone is accompanied by a loss of chromophores that absorb ultraviolet light and the appearance of a reddish brown color. Similarly, when the relatively low molecular weight auxin protectors (Pr-II class) were incubated with polyphenol oxidase, their oxidation was also frequently associated with the formation of brown color, and oxidation with H(2)O(2) caused a loss of ultraviolet-absorbing chromophores. The data indicate that auxin protectors contain o-dihydroxyphenolic groups at their active site.That o-dihydroxyphenols inhibit indoleacetic acid oxidation has been demonstrated by numerous workers. It is suggested that the high molecular weight auxin protectors and the phenolic compounds described by other authors comprise part of a metabolic system concerned with the regulation of peroxidase-catalyzed redox reactions.
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PMID:Studies on Auxin Protectors: IX. Inactivation of Certain Protectors by Polyphenol Oxidase. 1665 85

Vacuoles were isolated from suspension cultures of sugarcane (Saccharum sp.) cells by centrifugation of protoplasts at high g force against a 12% (w/v) Ficoll solution. Distribution of marker enzymes and Concanavalin A binding showed an 11% contamination of the vacuole preparation by cytoplasmic components, mitochondria, and endoplasmic reticulum, and 18% contamination by plasma membrane. Acid phosphatase, carboxypeptidase, protease, peroxidase, and ribonuclease activities were enriched in isolated vacuoles. Carboxypeptidase was tonoplast-bound, whereas the other enzymes were soluble. Sucrose, reducing sugars, and free amino acids were measured in protoplasts and vacuoles during growth of cells in suspension culture. Sucrose and reducing sugar content of vacuoles increased as the culture aged, while free amino acids decreased sharply.
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PMID:Vacuoles from Sugarcane Suspension Cultures : I. ISOLATION AND PARTIAL CHARACTERIZATION. 1666 93

Ethylene enhanced the senescence of cucumber (Cucumis sativus L. cv ;Poinsett 76') cotyledons. The effect of 10 microliters per liter ethylene was inhibited by 1 millimolar silver thiosulfate, an inhibitor of ethylene action. An increase in proteins with molecular weights of 33 to 30 kilodaltons and lower molecular weights (25, 23, 20, 16, 12, and 10 kilodaltons) were observed in sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels after ethylene enhanced senescence. The measurement of DNase and RNase activity in gels indicated that these new proteins were not nucleases. Two proteins from ethylene-treated cotyledons were purified on the basis of their association with a red chromaphore and subsequently were identified as peroxidases. The molecular weights and isoelectric points (pI) of two of these peroxidases were 33 kilodaltons (cationic, pI = 8.9) and 60 kilodaltons (anionic, pI = 4.0). The observation that [(35)S]Na(2)SO(4) was incorporated into these proteins during ethylene-enhanced senescence suggests that these peroxidases represent newly synthesized proteins. Antibodies to the 33-kilodalton peroxidase precipitated two in vitro translation products from RNA isolated from ethylene-treated but not from control cucumber seedlings. This indicates that the increase in 33-kilodalton peroxidase activity represents de novo protein synthesis. Both forms of peroxidase degraded chlorophyll in vitro, which is consistent with the hypothesis that peroxidases have catabolic or scavenging functions in senescent tissues.
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PMID:Induction of 33-kD and 60-kD Peroxidases during Ethylene-Induced Senescence of Cucumber Cotyledons. 1666 94

T cells recognize protein antigens as short peptides processed and displayed by antigen-presenting cells. However, the mechanism of peptide selection is incompletely understood, and, consequently, the differences in the immunogenicity of protein antigens remain largely unpredictable and difficult to manipulate. In this paper we show that the susceptibility of protein antigens to lysosomal proteolysis plays an important role in determining immunogenicity in vivo. We compared the immunogenicity of proteins with the same sequence (same T cell epitopes) and structure (same B cell epitopes) but with different susceptibilities to lysosomal proteolysis. After immunizing mice with each of the proteins adsorbed onto aluminum hydroxide as adjuvant, we measured serum IgG responses as a physiological measure of the antigen's ability to be presented on major histocompatibility complex class II molecules and to prime CD4+ T cells in vivo. For two unrelated model antigens (RNase and horseradish peroxidase), we found that only the less digestible forms were immunogenic, inducing far more efficient T cell priming and antibody responses. These findings suggest that stability to lysosomal proteolysis may be an important factor in determining immunogenicity, with potential implications for vaccine design.
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PMID:Enhancing immunogenicity by limiting susceptibility to lysosomal proteolysis. 1690 25

To elucidate the deleterious effects of excess lead on radish (Raphanus sativus) cv. Jaunpuri plants were grown in refined sand in complete nutrient solution for 30 days. On the 31st day lead nitrate was superimposed at 0.1 and 0.5mM to radish for 65 days. A set of plants in complete nutrient solution was maintained as control for the same period without lead. Excess Pb at 0.5mM showed growth depression with interveinal chlorosis on young leaves at apex. Excess Pb reduced the fresh and dry weight pronouncedly at d 65. Lead accumulation reduced the concentration of chlorophyll, iron, sulphur (in tops), Hill reaction activity and catalase activity whereas increased the concentration of phosphorus, sulphur (in roots) and activity of peroxidase, acid phosphatase and ribonuclease in leaves of radish.
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PMID:Excess lead alters growth, metabolism and translocation of certain nutrients in radish. 1792 49


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