Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rat liver rough microsomes (RM) contain two integral membrane proteins which are not found in smooth microsomes (SM) and appear to be related to the presence of ribosome-binding sites. These proteins, of molecular weight 65,000 and 63,000, were designated ribophorins I and II, respectively. They were not released from the microsomal membranes by alkali or acid treatment, or when the ribosomes were detached by incubation with puromycin in a high salt medium. The anionic detergent sodium deoxycholate caused solubilization of the ribophorins, but neutral detergents led to their recovery with the sedimentable ribosomes. Ribosomal aggregates containing both ribophorins, but few other membrane proteins, were obtained from RM treated with the nonionic detergent Kyro EOB (2.5 X10(-2) M) in a low ionic strength medium. Sedimentation patterns produced by these aggregates resembled those of large polysomes but were not affected by RNase treatment. The aggregates, however, were dispersed by mild trypsinization (10 microgram trypsin for 30 min at 0 degrees C), incubation with deoxycholate, or in a medium of high salt concentration. These treatments led to a concomitant degradation or release of the ribophorins. It was estimated, from the staining intensity of protein bands in acrylamide gels, that in the Kyro EOB aggregates there were one to two molecules of each ribophorin per ribosome. Sedimentable complexes without ribosomes containing both ribophorins could also be obtained by dissolving RM previously stripped of ribosomes by puromycin-KCl using cholate, a milder detergent than DOC. Electron microscope examination of the residue obtained from RM treated with Kyro EOB showed that the rapidly sedimenting polysome-like aggregates containing the ribophorins consisted of groups of tightly packed ribosomes which were associated with remnants of the microsomal membranes.
 ...
PMID:Proteins of rough microsomal membranes related to ribosome binding. I. Identification of ribophorins I and II, membrane proteins characteristics of rough microsomes. 64 58

The effects of salt, temperature, enzyme to DNA ratio, and heparin challenge on both total RNA synthesis and synthesis from specific promoters are examined using DNA from bacteriophages lambdacb2 and T7. Determination of synthesis from specific promoters is carried out by the fractionation and quantitation on polyethylenimine-cellulose thin-layer chromatograms of the 5'-terminal oligonucleotides produced by digestion of the RNA products with T1 RNase. The major findings of this work are that (1) lambdacb2 promoters are more salt sensitive than T7 promoters and the salt concentration affects individual promoters differently, (2) T7 promoters initiate maximally at 37 degrees C but the transition temperatures of promoters vary and may be dependent on the salt concentration, (3) increasing the enzyme to DNA ratio results in increasing initiations at the promoters on T7 DNA without causing measurable initiation at non-promoters, and (4) T7 and lambdacb2 promoters show differences in stability when challenged with heparin.
 ...
PMID:Selectivity of RNA chain initiation in vitro. 3. Variables affecting initiation of transcription. 66 11

A study was made of the levels of ribonuclease (RNase) in human serum, using 2 independently collected banks of samples from Scripps Clinic and Research Foundation and the Mayo Clinic, each bank representing more than 100 individuals. These serum samples originated from a cross-section of normal individuals, smokers, patients with benign tumours, and patients with a variety of neoplasms. Elevated levels of serum RNase occurred in 68% of the samples from individuals with malignant disease. Elevated levels also occurred in 24% of the samples from individuals with benign tumours and in 38% of the smoker controls from the Mayo Clinic serum bank. Using ion-exchange chromatography, pooled sera from normal individuals and cancer patients were fractionated by differential salt elution. Each pool showed 2 distinct peaks of RNase activity, and both peaks were elevated to the same degree in the cancer serum pools. Similar results were obtained after thin-layer-gel isoelectric focusing of both normal and cancer sera; no new species of RNase could be detected in the sera of patients with malignant diseases. The results suggested a generalized nonspecific increase in serum RNase in these patients.
 ...
PMID:Serum ribonuclease activity in cancer patients. 69 43

A rapid method is described for the simultaneous removal of contaminant ribonuclease activity and isolation of immunoglobulin G from fractionated or whole serum using insolubilized protein A. Protein A, isolated from the Cowan I strain of Staphylococcus aureus, was covalently attached to Sepharose CL-4B resin and used as a specific affinity absorbent for immunoglobulin G. Affinity column-purified immunoglobulin G preparations were examined for the presence of contaminating serum proteins, retention of antibody activity, and retention of antigenic properties. Following chromatography on protein A-Sepharose, immunoglobulin G preparations were devoid of contaminating serum proteins, in particular ribonuclease activity, that are not normally removed using conventional techniques of salt precipitation in combination with ion-exchange chromatography. There was no significant alteration of either antibody activity or antigenic properties of protein A-Sepharose purified immunoglobulin G.
 ...
PMID:The rapid isolation of ribonuclease-free immunoglobulin G by protein A-sepharose affinity chromatography. 72 86

RNA transcribed in vitro at low ionic strength, from either rat liver chromatin or DNA, contains a significant amount of structure resistant to RNase in high salt buffer. This is observed with rat liver (form B polymerase) as well as with Escherichia coli RNA polymerase (RNA nucleotidyltransferase; nucleoside triphosphate: RNA nucleotidyltransferase; EC 2.7.7.6). Treatment with RNases specific for either double-stranded or hybrid RNA indicates that resistance to RNase is due to the presence of double-stranded RNA sequences. Denaturation kinetics in the presence or absence of RNase suggest that these sequences are formed by intramolecular base pairing. Their mean length is about 20 to 30 nucleotides, but 15-20% are more than 100 nucleotides long. They contain 60-65% G-C base pairs. The proportion of double-stranded segments is higher in chromatin transcripts than in DNA-templated RNA, and is higher with homologous RNA polymerase than with the bacterial enzyme. On the other hand, chromatin endogenous RNA polymerase, which is unable to initiate transcription, does not synthesize double-stranded RNA. The problem of the location of these sequences is discussed; preliminary results suggest that the 5' end of the RNA transcripts could be enriched in complementary sequences.
 ...
PMID:Double-stranded RNA in chromatin transcripts formed by exogenous RNA polymerase. 77 79

A new procedure for R17 RNA preparation was devised using a 300 liters fermenter. The key factor in processing such a large quantity is the purification of phage particles prior to RNA extraction. The method involves the preparation of 250 liters of crude lysate, condensation of phage particles by the partition method, purification by DEAE-cellulose column, and removal of adherent proteins by a series of high-salt washes. The method permits preparation of approximately 3 g of phage particles free of ribosomal fragments and RNase. Phage RNA extracted in gram quantities using conventional methods often contain phenol. Thus repeated extraction of R17 RNA with salt-alcohol mixture is required.
 ...
PMID:R17 RNA replicase. VI. A large scale preparation of R17 template RNA. 77 22

T4 Species I RNA, a molecule 140 nucleotides in length with some structural features very much like a tRNA, is specifically cleaved by an enzymatic activity in Escherichia coli extracts to give three segments with 19, 48 and 73 nucleotides. We report the purification and characterization of the E. coli RNase which cleaves two 3' phosphodiester bonds of T4 Species I RNA. This reaction has many properties in common with those catalyzed by E. coli RNase III, although the optimal salt conditions for T4 Species I RNA cleavage differ significantly from those for other RNase III-catalyzed reactions. The reaction is not catalyzed by extracts from an E. coli strain lacking RNase III activity. Furthermore, T4 Species I RNA is cleaved by highly purified E. coli RNase III to yield the same three specific fragments. We conclude that this specific cleavage is due to the action of RNase III, and that the requirement for lower ionic strength may reveal further important properties about this RNA processing enzyme.
 ...
PMID:Cleavage of T4 species I ribonucleic acid by Escherichia coli ribonuclease III. 78 26

Bacteriophage T4-coded gene 32-protein is an essential component of the T4 replication and recombination systems. Alberts and co-workers (Alberts, B.M., Amodio, F.J., Jenkins, M., Gutmann, E.D., and Ferris, F.L. (1968) Cold Spring Harbor Symp. Quant. Biol. 33, 289-305) have shown that the major physiological activity of the protein involves preferential and cooperative binding to single-stranded DNA. In this paper, the physiochemical parameters characterizing this "melting" protein system are quantitatively determined. Boundary sedimentation velocity experiments are used to measure the interaction of gene 32-protein with native DNA. The binding is shown to be non-cooperative and involves an overlapping site size (nh) of approximately 10 nucleotide residues (or approximately 5 nucleotide pairs). In analogy with the ribonuclease results (Jensen, D.E., and von Hippel, P.H. (1976) J. Biol. Chem. 251, 7198-7214), the logarithm of the association constant (Kh) is found to be linerarly related to log [Na+]. The binding of gene 32-protein to denatured (single-stranded) DNA involves appreciable distortion of the polynucleotide backbone from the unliganded conformation; binding totally unstacks the bases of both ribose- and deoxyribose-containing polynucleotides at 10 degrees, and results in a hyperchromic change exceeding that which can be induced by heating. This hyperchromism induced in poly(dA) on binding gene 32-protein under low salt (tight binding) conditions is used to determine a value of nc (the single-stranded DNA site size) of approximately 6.7 nucldotide residues per protein. In addition, gene 32-protein binding to single-stranded polynucleotide induces an unusual circular dichroic spectrum characterized principally by a marked decrease in the magnitude of the positive CD band centered at approximately 265 nm. This spectral change is attributed to significant uncoupling of the transition moments of the vicinal bases of the single-stranded polynucleotide on gene 32-protein binding, in accord with the ultraviolet hyperchromism observed. Binding of gene 32-protein to double helical DNA has virtually no effect on the spectral properties of this conformation...
 ...
PMID:DNA "melting" proteins. II. Effects of bacteriophage T4 gene 32-protein binding on the conformation and stability of nucleic acid structures. 79 45

Cells of Bacillus subtilis heated in high concentrations of sodium dodecyl sulfate (5%) and then washed free of detergent with a hot salt solution (80 C) become structurally reorganized into regions of densely compacted cytoplasm (termed zebras) and regions of sparsely filled material (termed spaces). Size distribution studies of zebras indicate that division-suppressed mutants and wild-type cells both yield zebras of comparable length. Similarly the lengths of zebras found in populations emerging from spores are uniform in one-, two-, three-, and four-zebra-containing cells. In contrast, the length of spaces is slightly larger than that of zebras and is unusually large in two-zebra-containing cells. The locations of zebras and spaces along cell length have been studied in spore out-growth populations. A statistical procedure developed previously in genome location investigations was used to analyze the location of zebras along cell length. The data indicate that as cells elongate, new sites arise where the cell contents are strongly bound to the cell surface. Within filament populations produced by division-suppressed mutants there is a linear relationship of mean filament length and zebra number per filament. These data indicate that cytoplasm in filaments with no obvious structural compartmentalizations may be organized into units associated with particular regions of cell surface. The attachment of cell contents to the cell surface may involve deoxyribonucleic acid. Zebra-containing cells digested with proteolytic enzyme and ribonuclease are converted to cells that contain a crystalline-like granule fixed at the location of each zebra. Exposure to deoxyribonuclease mobilizes these granules within the cell wall.
 ...
PMID:Cellular organization of Bacillus subtilis: sodium dodecyl sulfate-induced cell partitioning into zebra structures. 82 Jun 87

The lateral mobility of ribosomes bound to rough endoplasmic reticulum (RER) membranes was demonstrated under experimental conditions. High-salt-washed rough microsomes were treated with pancreatic ribonuclease (RNase) to cleave the mRNA of bound polyribosomes and allow the movement of individual bound ribosomesmfreeze-etch and thin-section electron microscopy demonstrated that, when rough microsomes were treated with RNase at 4 degrees C and then maintained at this temperature until fixation, the bound ribosomes retained their homogeneous distribution on the microsomal surface. However, when RNase-treated rough microsomes were brought to 24 degrees C, a temperature above the thermotropic phase transition of the microsomal phospholipids, bound ribosomes were no longer distributed homogeneously but, instead, formed large, tightly packed aggregates on the microsomal surface. Bound polyribosomes could also be aggregated by treating rough microsomes with antibodies raised against large ribosomal subunit proteins. In these experiments, extensive cross-linking of ribosomes from adjacent microsomes also occurred, and large ribosome-free membrane areas were produced. Sedimentation analysis in sucrose density gradients demonstrated that the RNase treatment did not release bound ribosomes from the membranes; however, the aggregated ribosomes remain capable of peptide bond synthesis and were released by puromycin. It is proposed that the formation of ribosomal aggregates on the microsomal surface results from the lateral displacement of ribosomes along with their attached binding sites, nascent polypeptide chains, and other associated membrane proteins; The inhibition of ribosome mobility after maintaining rough microsomes at 4 degrees C after RNase, or antibody, treatment suggests that the ribosome binding sites are integral membrane proteins and that their mobility is controlled by the fluidity of the RER membrane. Examination of the hydrophobic interior of microsomal membranes by the freeze-fracture technique revealed the presence of homogeneously distributed 105-A intramembrane particles in control rough microsomes. However, aggregation of ribosomes by RNase, or their removal by treatment with puromycin, led to a redistribution of the particles into large aggregates on the cytoplasmic fracture face, leaving large particle-free regions.
 ...
PMID:Mobility of ribosomes bound to microsomal membranes. A freeze-etch and thin-section electron microscope study of the structure and fluidity of the rough endoplasmic reticulum. 83 67


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>