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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The method of Ramsey and Steele [Anal. Biochem., 92 (1979) 305--313] was used to examine the size distribution of membrane-bound and free polyribosomes from the liver of male C57 BL/6 mice over the life span. Optimization of the concentration of Mg2+ and liver cell sap suppressed breakdown by ribonuclease and presumably gave preparations that approximate the integrity of native polyribosome populations. The content of polysomes per unit liver tissue from 7 groups of fed mice aged 10--35 months showed an age-related increase of subunits and monomers (+54%) and dimers-to-pentamers (+76%) in membrane-bound polyribosomes. The dimer-to-pentamer class of free polyribosomes also increased (+52%). Polysomes larger than nonamers showed 13% and 21% decreases that were not statistically significant. Total tissue ribosomes increased 15%, while the membrane-bound/free polyribosome ratio remained nearly constant at about 1.15. In a subsequent study, both 6 h-fasted and fed mice showed decreases (-20% to -33%) in membrane-bound and free polyribosomes larger than nonamers during aging from 15 to 35 months. The dimer-to-pentamer class of free polyribosomes in fed mice increased (+26%), while this class in the other groups underwent increases (+26 to +39%) that were not statistically significant. We conclude that the liver in old mice is not obviously deficient in either quantity or general quality of ribosomes. Old animals do tend to show an increase in small polysomes and a decrease in large polysomes, which is consistent with a reduction in the rate of translation.
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PMID:The content and size distribution of membrane-bound and free polyribosomes in mouse liver during aging. 649 84

During growth and maturation of the tapeworm, Hymenolepis diminuta, significant decreases occur in the brush border membrane-bound alkaline phosphatase, phosphodiesterase, 5'-nucleotidase, adenosine triphosphatase and ribonuclease activities. These decreases are accompanied by qualitative and quantitative changes in the polypeptide profiles of the brush border membrane fraction. Gradients of enzymatic activities and polypeptide profiles are also demonstrable when mature tapeworms are cut into pieces and the brush border membrane of each piece analyzed individually. In fully developed tapeworms the enzymatic activities and polypeptide profiles of membrane preparations reflect mainly the contributions of the more mature proglottids; these proglottids constitute most of the tapeworm biomass. The most anterior sections of these fully developed worms are biochemically similar to young, developing worms.
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PMID:Alterations in brush border membrane proteins and membrane-bound enzymes of the tapeworm, Hymenolepis diminuta, during development in the definitive host. 663 65

Previously we reported that chronic renal failure in rats leads to preferential disaggregation of liver membrane-bound polysomes associated with a decrease in albumin synthesis. To determine whether reduced albumin synthesis results from reduced cellular levels of albumin messenger RNA (mRNA) or some other molecular mechanism, we have employed mRNA-DNA hybridization in conjunction with cell-free protein synthesis to determine albumin mRNA sequence content and biological activity in subcellular fractions from control and uremic rat liver. Using high specific activity albumin [3H]-complementary DNA prepared from purified-albumin mRNA, we found that total liver polysomes and albumin mRNA sequence content are increased in uremic animals. The extra polysomes are located within the membrane-bound subcellular fraction. These polysomes, however, have reduced ability to synthesize albumin in the cell-free system, and mRNA isolated from membrane-bound polysomes of uremic liver showed reduced albumin synthesis. Evaluation of albumin mRNA size by hybridization analysis revealed a reduced content of intact albumin mRNA molecules per microgram of RNA in the liver of uremic animals. This was associated with increased ribonuclease activity in uremic cytosol. The diminished albumin synthesis by membrane-bound polysomes of uremic rat liver can, therefore, be explained by enhanced degradation of albumin mRNA.
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PMID:Effects of chronic renal failure on protein synthesis and albumin messenger ribonucleic acid in rat liver. 670 9

The effects of trichloroethylene (TCE) and acrylonitrile (ACN) on growth, RNA synthesis, ribosome synthesis, and ribosome content were tested in yeast cells. TCE causes a delay of the growth of a cell culture (prolongation of the lag phase), but does not cause inhibition. Cells exposed to increasing concentrations of ACN show increasing damage, so that, at a certain point of the growth curve, cell division stops altogether. Similar results were obtained when RNA synthesis was investigated: After treatment with TCE, the maximum RNA synthesis of the cell culture was retarded, but subsequently reached the same level as the untreated control cells. In the presence of ACN, however, the rate of RNA synthesis was lowered with increasing ACN concentrations. The same effect was observed upon investigation of ribosome synthesis: Whereas TCE produces only a slight effect, treatment with increasing concentrations of ACN leads to a substantial decrease in ribosome synthesis, and finally to total inhibition. Parallel to this, the content of free and membrane-bound ribosomes is diminished. Obviously, the decrease in ribosome content is caused not only by an inhibition of ribosome synthesis, but also by a degradation of existing ribosomes, as well as by induction of a ribosome-associated RNase.
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PMID:The effect of trichloroethylene and acrylonitrile on RNA and ribosome synthesis and ribosome content in Saccharomyces cells. 671 40

Acholeplasma laidlawii A has been grown in media containing synthetic, long chain C20- and C23-fatty acids possessing a diacetylene group in their acyl chains. Growth on the C23 diacetylenic acid was poor but was good on the C20 acid. Biosynthetic incorporation of the fatty acids occurs; as much as 90% of the membrane lipid fatty acyl chains consisting of the C20-diacetylenic fatty acid, the remainder being shorter chain, saturated fatty acids. The thermal phase transition of this biomembrane has been studied and a differential scanning calorimetry heating curve shows the presence of an endotherm corresponding to a membrane lipid phase transition occurring at about 26 degrees C. The lipid class composition of membranes containing the C20-diacetylene lipids was examined and found to be similar to membranes from cells grown on oleic acid-containing medium. (The ratio of monoglucosyl- to diglucosyldiacylglycerols was the same but the ratio of glycolipid to phosphatidylglycerol was higher in the cells grown with diacetylene fatty acids). Upon irradiation with ultraviolet light the cells and isolated biomembranes become coloured, either red or yellow depending upon their thermal history. The colour change indicates that extensive cross-linking of the lipids of the biomembranes of A. laidlawii has occurred and that a conjugated polymeric structure has been formed. Analysis of the extracted lipids from the biomembranes by GLC indicates that extensive cross-linking of the lipid chains within the biomembrane of a natural cell system has been achieved. The monoglucosyldiacylglycerols cross-link more readily that do the phosphatidylglycerol lipids. The effect of such lipid cross-linking or polymerisation on the activity at 35 degrees C of an intrinsic membrane-bound enzyme, NADH oxidase, and ribonuclease, an extrinsic membrane-bound enzyme, was studied. The NADH oxidase activity decreased rapidly upon cross-linking of the lipid environment whereas ribonuclease activity was unaffected. The potential for future studies of polymerised model and natural biomembranes is discussed.
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PMID:The biosynthetic incorporation of diacetylenic fatty acids into the biomembranes of Acholeplasma laidlawii A cells and polymerisation of the biomembranes by irradiation with ultraviolet light. 683 76

The 38,000-Mr poly(A)-binding protein has been purified to near homogeneity from non-polysomal messenger ribonucleoprotein of Artemia salina [Slegers, H., De Herdt, E., and Kondo, M. (1981) Eur. J. Biochem. 117, 111-120]. The protein consists of approximately 357 amino acids and is characterized by a high glycine content of 22.5% and the presence of dimethylarginine. From polynucleotide-protein binding experiments a stoichiometry of 9-11 adenylate and 10-12 uridylate residues per protein molecule is calculated. The polypeptide is devoid of poly(A) polymerase and RNase activities. The poly(A)-binding protein and the helix-destabilizing protein HD40 [Marvil, D. K., Nowak, L., and Szer, W. (1980) J. Biol. Chem. 255, 6466-6472] have the same mobility in polyacrylamide/dodecylsulphate gel electrophoresis and exhibit a comparable amino acid composition and protein-polynucleotide stoichiometry. Based on the length of poly(A) sequences of mRNA and from protein-poly(A) binding experiments, a repetitive binding of the 38,000-Mr protein on the poly(A) sequence is demonstrated. The 38,000-Mr protein of cytoplasmic and membrane-bound non-polysomal messenger ribonucleoproteins is also compared.
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PMID:The 38,000-Mr poly(A)-binding protein of non-polysomal messenger ribonucleoproteins of cryptobiotic gastrulae of Artemia salina. 706 May 86

The structure of the free zoospores of Neocallimastix frontalis has been examined by electron microscopy of thin-sectioned and negatively stained preparations. There are up to 15 flagella arranged in two rows. The free end of each flagellum is narrow and its tip does not contain microtubules. The flagella and the cell body are coated with distinct surface layers composed of regular arrays of particles and fibrils, respectively. The cell body contains a variety of inclusions. Near to the flagellar pole there are numerous membrane-bound electron-dense globules about 0.2 to 0.7 mum in diameter, between which are microtubules, particles and small vesicles. In the region of the centrally placed nucleus are arrays of helices of ribosome-like particles. These particles also occur in the form of globular aggregates, each partially enclosed within a membrane. The remainder of the cytoplasm is filled with material resembling glycogen. The zoospores stain positively for glycogen and contain ribonuclease-sensitive particulate material which is stained by toluidine blue. Scanning electron microscopy shows that the zoospores attach to the substrate by the flagellar pole.
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PMID:Ultrastructural studies of the free zoospore of the rumen phycomycete Neocallimastix frontalis. 719 79

Plasma membrane from the brush border isolated from the tegument of Hymenolepis diminuta contains membrane-bound ribonuclease (RNase) and alkaline phosphatase activities. RNase (yeast RNA substrate), alkaline phosphatase (p-nitrophenyl phosphate substrate), and additional membrane proteins were solubilized by sonication or treatment with the detergents dodecyl trimethylammonium bromide, beta-octyl-D-glucopyranoside, sodium dodecyl sulfate (SDS), or ZwittergentTM 3-12 (N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate). At optimal conditions, greater than 90% of both enzymes and total protein were solubilized by the latter two detergents, whereas beta-octyl-D-glucopyranoside, dodecyl trimethylammonium bromide, and sonication were only partially effective. Nonionic detergents did not solubilize the membrane effectively.
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PMID:Solubilization of membrane-bound ribonuclease (RNAse) and alkaline phosphatase from the isolated brush border of Hymenolepis diminuta (Cestoda). 739 87

Transforming growth factor beta 1 (TGF-beta 1), a product of marrow stromal cells, inhibits the proliferation and differentiation of hematopoietic progenitor cells within the hematopoietic microenvironment. Steel factor (SF), also a product of marrow stromal cells, is an essential positive regulator of hematopoiesis in vivo. TGF-beta 1 has been shown to repress human and murine leukemic cell and murine lin- bone marrow mononuclear cell expression of the receptor for SF (c-kit). We speculated that TGF-beta 1 might exert its inhibitory effect on hematopoiesis in part by decreasing SF/c-kit interactions. Therefore, we tested the hypothesis that TGF-beta 1 inhibits both stromal cell expression of SF and hematopoietic progenitor cell expression of c-kit. We measured stromal cell expression of SF protein and hematopoietic progenitor cell expression of membrane-bound c-kit before and after exposure to recombinant human TGF-beta 1. Both stromal cell expression of SF protein and hematopoietic progenitor cell expression of c-kit protein were inhibited 50% to 80% by TGF-beta 1. Using Northern blot and ribonuclease protection assays, we determined that TGF-beta 1 repressed stromal cell SF mRNA, but did not alter SF transcript stability. TGF-beta 1 was also found to repress c-kit mRNA in human leukemic myeloblasts as well as in normal lin- hematopoietic progenitor cells. In contrast with its effect on SF mRNA, TGF-beta 1 accelerated the degradation of c-kit mRNA. We conclude that TGF-beta 1 inhibits stromal cell production of SF by repression of SF gene transcription and represses hematopoietic progenitor cell expression of c-kit by decreasing the stability of c-kit transcripts. Taking into account the importance of SF and c-kit in maintaining steady-state hematopoiesis in vivo, the dual effect of TGF-beta 1 on both SF and c-kit gene expression is likely to be one of the major mechanisms by which TGF-beta 1 inhibits hematopoiesis in vivo.
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PMID:Transforming growth factor beta 1 inhibits expression of the gene products for steel factor and its receptor (c-kit). 753 88

The mannose 6-phosphate (Man6P)-dependent pathway for routing lysosomal enzymes was characterized in the hepatopancreas of the estuary crab Chasmagnatus granulata: (a) an acid alpha-L-fucosidase was purified to homogeneity from the above-mentioned organ and was shown to contain mannose-linked phosphate residues; (b) high-mannose-type oligosaccharides isolated from a protein fraction enriched in acid hydrolases were found to contain acid-labile N-acetylglucosamine (GlcNAc) residues; (c) a membrane-bound UDP-GlcNAc:lysosomal enzyme GlcNAc-1-phosphotransferase was detected that phosphorylated the estuary-crab alpha-L-fucosidase and bovine uteroferrin but not bovine pancreas ribonuclease B; (d) a GlcNAc-1-phosphodiester alpha-N-acetylglucosaminidase that released GlcNAc units from GlcNAc alpha 1-P6Man alpha 1-methyl was detected in microsomal membranes of the hepatopancreas; (e) two detergent-solubilized microsomal proteins having molecular masses of 205 and 215 kDa that were retained by a Man6P-rich mannan-Sepharose column, from where they were eluted with Man6P but not with glucose 6-phosphate, were recognized by antisera raised against bovine large (215 kDa) and small (46 kDa) Man6P receptors. This is the first description of all the components of the Man6P-dependent mechanism for routing lysosomal enzymes in an invertebrate.
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PMID:Characterization of the mannose 6-phosphate-dependent pathway of lysosomal enzyme routing in an invertebrate. 765 99


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