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)

The effect of RNase on the transformation of progesterone receptor from rabbit uterus was studied by density-gradient centrifugation and DNA-cellulose binding assay. The 7S form of the receptor in crude cytosol was RNase sensitive, and converted to the 4S form after RNase treatment. This reaction was prevented by an RNase inhibitor and reversed by the addition of ribosomal RNA. RNase treatment also caused a two-fold increase in the DNA binding of cytosolic receptor, and reduced the time required for heat-induced transformation. However, sucrose-gradient-purified progesterone receptor (7S) did not undergo transformation by warming unless exogenous RNase was added, thereby suggesting that a cytosolic factor, which might be endogenous RNase, is necessary for the heat-induced transformation of progesterone receptor. Furthermore, degradation of the receptors which occurred after prolonged warming at 25 degrees C in the presence of RNase could be prevented by the addition of DNA-cellulose to the reaction mixture. These results indicate that RNA is associated with the 7S form of progesterone receptor, and that its hydrolysis by RNase might be involved in the transformation of this receptor.
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PMID:Ribonuclease-induced transformation of progesterone receptor from rabbit uterus. 242 51

Angiogenin is a 14 kD protein, initially isolated as a tumour-cell secreted product but subsequently found to be a normal constituent of human plasma. It is a potent inducer of blood vessel formation on the chorioallantoic membrane of the chick embryo. Chemical characterization of the protein reveals a remarkable homology to the pancreatic ribonuclease family and has led to the identification of a unique ribonucleolytic activity for angiogenin. It is a particularly potent inhibitor of in vitro protein synthesis. Treatment with placental ribonuclease inhibitor abolishes the biological and enzymatic activities of angiogenin, an effect with important mechanistic, physiological and pharmacologic implications.
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PMID:Human angiogenin, an organogenic protein. 245 89

The cytosolic untransformed molybdate-stabilized glucocorticoid-receptor complex from rat liver was eluted as a heterogenous peak containing two components with Stokes radii (Rs) of 8.3 nm and 7.1 nm when analyzed by size-exclusion HPLC even in the absence of molybdate. In contrast, the highly purified glucocorticoid receptor yielded a sharp symmetrical peak of Rs = 7.1 nm. We demonstrate that the 7.1-nm component could not result from a proteolytic degradation of the 8.3-nm receptor form. The same receptor heterogeneity was observed in thymus cytosol which contains less proteases than liver. After labeling with [3H]dexamethasone 21-mesylate and SDS/PAGE the same 94-kDa receptor band was revealed in both the 8.3-nm and 7.1-nm forms. Immunoblotting experiments showed that both the 94-kDa hormone-binding subunit and the 90-kDa heat-shock protein were present in the two different receptor forms. The 8.3-nm receptor form was converted to the 7.1-nm receptor form after treatment by ribonuclease A in the presence of molybdate and this effect was dose-dependent, being completely prevented by placental ribonuclease inhibitor (RNasin). In contrast, in the presence of molybdate, the 7.1-nm receptor form was ribonuclease-insensitive. Treatment of cytosol with RNase A in the absence of molybdate, partially shifted the untransformed receptor towards the 5.2-nm transformed receptor form. This effect was abolished by placental ribonuclease inhibitor. RNase S protein, an enzymatically inactive proteolytic fragment of RNase A, or S1 nuclease, which is specific for single-stranded nucleic acids, were ineffective when used instead of RNase A. In contrast, cobra venom endonuclease, which preferentially attacks double-stranded regions of small RNAs, caused a complete conversion of the 7-8-nm untransformed receptor to the 5.2-nm transformed receptor form. These results were not observed in the presence of molybdate. Addition of RNasin prior to heating cytosol in the absence of molybdate did not prevent the receptor from dissociating to the 5.2-nm form, suggesting that an endogenous RNase is not involved in the transformation process. The 7.1-nm receptor form was shifted to a 9.2-nm complex when incubated with an excess of GR 49 antireceptor antibody, whereas the 8.3-nm receptor form did not bind to the antibody.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:RNA binding to the untransformed glucocorticoid receptor. Sensitivity to substrate-specific ribonucleases and characterization of a ribonucleic acid associated with the purified receptor. 246 3

Human placental ribonuclease inhibitor (PRI) has been expressed in and isolated from Escherichia coli. Its apparent molecular weight, immunoreactivity and amino acid composition are virtually identical with those of native PRI. It inhibits the enzymatic activities of either angiogenin, a blood vessel inducing protein homologous to pancreatic RNase (RNase A), or RNase A in a stoichiometry of 1:1. Recombinant PRI binds to angiogenin and RNase A with Ki values of 2.9 x 10(-16) M and 6.8 x 10(-14) M, respectively, comparable to the affinities of native PRI for these enzymes. Thus, these results confirm that PRI inhibits angiogenin more effectively than RNase A.
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PMID:Expression of human placental ribonuclease inhibitor in Escherichia coli. 265 13

The binding of human placental ribonuclease inhibitor (PRI) to angiogenin, a human protein that induces neovascularization, occurs with a 1:1 stoichiometry and is accompanied by a 50% increase in tryptophan fluorescence. In contrast, the binding of PRI to bovine pancreatic RNase A or to angiogenin oxidized at its single tryptophan residue results in a quenching of fluorescence. These observations suggest that there is a change in the local environment of Trp-89 of angiogenin. Quenching experiments with acrylamide are consistent with the view that Trp-89 is exposed in the native protein and becomes less accessible upon formation of the complex with PRI. Stopped-flow kinetic measurements monitoring the fluorescence enhancement indicate a two-step mechanism for the binding of PRI to angiogenin. The first step involves rapid formation of an enzyme-inhibitor complex, EI, followed by a slower isomerization of EI to a tight enzyme-inhibitor complex, EI*: (Formula: see text). In 0.1 M NaCl at pH 6 and 25 degrees C, the values of K1 and K2 are 0.53 microM and 97 s-1, respectively. The apparent second-order rate constant of association at protein concentrations much less than K1 is approximated by K2/K1 and equals 1.8 X 10(8) M-1 s-1. The corresponding value for the association of PRI with RNase A is only slightly higher, 3.4 X 10(8) M-1 s-1. The effects of pH and sodium chloride concentration on the association rate of PRI with angiogenin suggest the importance of ionizable groups and ionic interactions, respectively, in the association process.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Tryptophan fluorescence as a probe of placental ribonuclease inhibitor binding to angiogenin. 270 45

The dissociation rate constant of the angiogenin-placental ribonuclease inhibitor complex was determined by measuring the release of free angiogenin from the complex in the presence of scavenger for free placental ribonuclease inhibitor (PRI). In 0.1 M NaCl, pH 6, 25 degrees C, this value is 1.3 X 10(-7) s-1 (t1/2 congruent to 60 days). The Ki value for the binding of PRI to angiogenin, calculated from the association and dissociation rate constants, is 7.1 X 10(-16) M. The corresponding values for the interaction of RNase A with PRI, determined by similar means, are both considerably higher: the dissociation rate constant is 1.5 X 10(-5) s-1 (t1/2 = 13 h), and the Ki value is 4.4 X 10(-14) M. Thus, PRI binds about 60 times more tightly to angiogenin than to RNase A. The effect of increasing sodium chloride concentration on the binding of PRI to RNase A was explored by Henderson plots. The Ki value increases to 39 pM in 0.5 M NaCl and to 950 pM in 1 M NaCl, suggesting the importance of ionic interactions. The mode of inhibition of RNase A by PRI was determined by examining the effect of a competitive inhibitor of RNase A, cytidine 2'-phosphate, on the association rate of PRI with RNase A. Increasing concentrations of cytidine 2'-phosphate decrease the association rate in a manner consistent with a competitive mode of inhibition.
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PMID:Tight-binding inhibition of angiogenin and ribonuclease A by placental ribonuclease inhibitor. 270 46

Acidic and alkaline RNase activity from healthy humans and gastric cancer patients has been studied. A decrease in daily saliva production and an increase in RNase activity was detected saliva of cancer patients. This suggests the existence of RNase inhibitors in healthy humans. This supposition is further confirmed by comparative analysis of total, joint fractional and reconstituted RNase activity. A considerable increase in acidic RNase inhibitors and disappearance of alkaline RNase inhibitor was observed in cancer patients. The specificity, mechanisms and clinical significance of this phenomena has been discussed.
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PMID:[Regulation of the RNAse activity of the saliva in healthy subjects and in stomach cancer]. 271 95

Human poly (C) avid serum ribonuclease (RNase) differs in physico-chemical, electrophoretic, and catalytic properties from ribonuclease activity encountered in liver preparations. The first is reported as "secretory type", the latter, because it is undetectable in body fluids, as "nonsecretory type". We determined RNase activity in 11 hepatoma patients. A statistical difference from a normal control of corresponding age was encountered in both age groups investigated (51-60 years, P less than 0.05; 61-70 years, P less than 0.01). The circumstances mentioned above make the tumor itself unlikely to be the source of RNase elevation. Besides a diminished synthesis of RNase inhibitor by hepatoma cells, tumor-derived polyamines could contribute to enhanced RNase activity. The influence of polyamines on RNase activity has already been demonstrated by in vitro experiments. Simultaneous estimation of polyamines and RNase is required to elucidate in vivo circumstances.
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PMID:Estimation of poly (C) avid serum ribonuclease in hepatoma patients. 303 38

Angiogenin, which induces the formation of new blood vessels, was isolated previously from two human sources--HT-29 tumor conditioned media and normal plasma. By use of a newly developed binding assay, a similar protein has now been purified from bovine plasma at levels of 30-80 micrograms/L. This protein has the structural, enzymatic, and biological characteristics expected for an angiogenin molecule. Its amino acid composition is similar to that of the human protein, and 22 of 31 residues in the amino-terminal sequences are identical, including a block of 11 consecutive residues. Like human angiogenin, the bovine protein binds placental ribonuclease inhibitor, is inactive toward conventional RNase A substrates, and displays selective ribonucleolytic activity toward some rRNAs. In addition, the bovine protein induces angiogenesis in vivo in the chick embryo chorioallantoic membrane assay at levels as low as 44 fmol per egg. Thus, angiogenin is present in bovine sera at levels similar to those observed in man, and its enzymatic and biological activities are identical with those of the human protein.
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PMID:Isolation of bovine angiogenin using a placental ribonuclease inhibitor binding assay. 306 6

Messenger RNAs in eukaryotic cells exhibit a broad range of stabilities in vivo. Globin mRNA has a half life in excess of 50 h, but the half life of the c-myc oncogene mRNA is less than 20 min. Regulation of gene expression may be accomplished by a variety of mechanisms, including altering mRNA stability. We have examined the nuclear and cytoplasmic fractions of cells for factors affecting the metabolism of mRNA. Here we report that a HeLa whole-cell extract contains a factor that protects beta-globin mRNA from attack by RNases in a mouse erythroleukemia cell cytoplasmic extract. The factor is non-dialysable, inactivated by proteinase K and heat treatment, and resistant to RNase and DNase digestion. The HeLa cell factor resembles placental RNase inhibitor in that the mRNA-protecting activity is effective against RNase A and that treatment of the extract with N-ethylmaleimide completely destroys the protective activity. However, purified placental RNase inhibitor was unable to inhibit the RNase activity in the MELC cytoplasmic extract. These results suggest that the HeLa cell extract contains an RNase inhibitor (or inhibitors) with an activity or specificity that is distinct from that of placental RNase inhibitor.
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PMID:Cellular factor affecting the stability of beta-globin mRNA. 316 61


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