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 half-life of cardiac myosin heavy chains (HC) was determined, with leucyl-tRNA as precursor, to be 5.4 days. Myosin HC are labeled more rapidly than actin; myosin light chains (LC1 and LC2) are labeled more slowly than HC. The observed differences are attributable to heterogeneity in the half-lives, e.g., actin, and to the effect of dilution by the existing macromolecular precursor pool (LC1 and LC2). Cardiac and skeletal muscle contain a population of filaments that can be released from myofibrils by ATP-relaxing solution. The easily released filaments (ERF) are devoid of alpha-actinin and M-protein. Labeling of ERF is more rapid than that of residual myofibrils. Cardiac and skeletal muscle contains calcium-activated neutral protease, which selectively removes alpha-actinin when incubated with isolated myofibrils. During development of pressure-induced cardiac hypertrophy, the labeling of LC2 is increased. In regressing cardiac hypertrophy the activities of free and total cathepsin D and of acidic RNase are unaltered.
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PMID:The pathways of protein synthesis and degradation in normal heart and during development and regression of cardiac hypertrophy. 14 38

From Tetrahymena macronuclei we have isolated a reversibly contractile nucleo-skeleton, i.e., an "expanded" nuclear matrix which reversibly contracts when the total concentration of the bivalent cations, Ca and Mg (3:2), is decreased to 5 mM or increased to 125 mM. During contraction the average diameter of the expanded matrix becomes reduced by about 24%; this corresponds to a volume contraction of about 55%. The reversible contraction of the nuclear matrix does not depend on ATP and cannot be inhibited by salygran. The expanded matrix is obtained by removing carefully from the macronuclei 89.7% of the phospholipid, 99.6% of the DNA, 98.5% of the RNA, and 74.8% of the protein by treatment with Triton X-100 and digestion with DNase and RNase followed by an extraction with 2 M NaCl. Electron microscopy reveals, within the expanded matrix, residual equivalents to the structures characteristic for macronuclei: (a) a residual nuclear envelope with nuclear pore complexes; (b) residual nucleoli at the periphery; (c) a fibrillar internal network. The expanded matrix is essentially composed of proteins (96.2%) and traces of DNA (0.8%), RNA (0.5%), phospholipid (1.6%), and carbohydrates (0.9%). The last, which have been determined by gas chromatography, contain glucose, mannose, and an unidentified sugar in the ratio 1:5.4:5.7. The ratio of acidic to basic amino acids of the expanded matrix is 1.55. Sodium dodecyl sulfate (SDS) gel electrophoresis reveals a predominant protein with a mol wt of 18,000 which is apparently involved in the reversible contractile process. The mechanism of this reversible contraction of the expanded matrix remains to be elucidated, but it differs both from actin-myosin contraction systems and from the contractile spasmoneme system in vorticellids.
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PMID:Reversibly contractile nuclear matrix. Its isolation, structure, and composition. 40 99

Myosin purified from Dictyostelium amoebae has approximately 10% by weight of RNA associated with it, unless specific steps (DEAE cellulose chromatography or RNase digestion) are taken to remove it. This RNA has significant effects on the structural states formed by the myosin at low ionic strength in the presence of Mg2+. Rapid precipitation of RNA-free myosin by dilution generates bipolar thick filaments (540 nm long, 33 nm thick), often with a bare zone and a 15-nm transverse repeat. Rapid precipitation of myosin with copurified RNA yields linear aggregates of bipolar filaments, showing some lateral association. Slow precipitation of RNA-free myosin by dialysis yields very long filaments or ribbons (greater than 5 micrometer, 30--60 nm wide) in which the myosin may be packed diagonally across the filament, similar to the "side-polar" aggregates formed by other nonmuscle myosins and by smooth muscle myosin (Craig R, Megerman J: J Cell Biol 75:990, 1977; Hinssen H, D'Haese J, Small JV, Sobieszek A: J Ultrastruct Res 64:282, 1978). Slow precipitation of myosin with copurified RNA generates linear filaments with repeat intervals of 290 and 650 nm. Other polyanions were tested for their effects on myosin aggregation. Total RNA and ribosomal RNA from Dictyostelium, when added to RNA-free myosin, also induced the extensive linear aggregation seen with the copurified RNA/myosin complex, although higher concentrations of RNA were required to obtain quantitatively the same effect. DNA and heparin were also effective inducers of linear aggregation, whereas homopolymers of nucleotides and of acidic or basic amino acids were poorly effective.
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PMID:Structural states of dictyostelium myosin. 54 31

Possibility was investigated to prepare polysomes from microsomal fraction of rat sceletal muscles. Centrifugation in sucrose gradient showed that approximately 60 percent of UV-absorbing material in the preparation obtained was in polysomic region of the gradient. Mild treatment with pancreatic ribonuclease led to disintegration of polysomes and respective increase in content of monosomic component. The use of combined gradient permitted to obtain two fractions of polysomes, one of which was readily sedimented by centrifugation. This fraction contained significant amount of protein and incorporated relatively low quantity of 32-P within 2 hrs after administration of the label in vivo. The data obtained suggest that the fraction of polysomes carried out the biosynthesis of myosin.
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PMID:[Isolation and some properties of rat skeletal muscle polysomes]. 113 99

Muscle translational-control RNA (tcRNA) has been separated into two classes, polysomal and messenger ribonuclear protein (mRNA - protein), which have different sizes as determined by acrylamide gel electrophoresis. While normally translation of mRNA - protein mRNA is inhibited by tcRNA derived from the same mRNA - proteins, this inhibition does not occur if the messenger is previously de-adenylated. This suggests that the poly(A) segment of mRNA is required for the tcRNA activity. Utilizing different mRNA - protein fractions from muscle, myosin mRNA - protein and small mRNA - proteins ( less than 30 S), we have been able to demonstrate that a degree of specificity exists in the interaction of tcRNA and mRNA derived from the same mRNA - proteins. This is illustrated by the facts that (a) each tcRNA only inhibits the translation of its respective mRNA and (b) the highest percentage of structural change occurs when each tcRNA is hybridized to its respective mRNA as measured by its resistance to T1 and T2 RNase.
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PMID:Studies concerning the mechanism by which translational-control RNA regulates protein synthesis in embryonic muscle. 123 5

In the heart, mRNA accumulations for sarcomeric actins and myosin heavy chains (MHC) are subject to diverse regulatorial processes. To study cardiac contractile protein transcriptional regulations, an in vitro transcription system using nonenzymatically isolated rat cardiac nuclei was characterized. Transcription was shown to be rapid and continuous during the first 20 min of incubation and 5.4-fold less than that seen from comparably isolated hepatocyte nuclei. Neither RNase nor DNase activities were detectable. Direct transcriptional analyses of the alpha- and beta-MHC and cardiac and skeletal alpha-actin genes from cardiac nuclei were performed. In 23-24-day-old rats, significant levels of transcription were seen for alpha-MHC and for the sarcomeric alpha-actins. beta-MHC was just detectable, and no positive signals were ever seen for fibronectin. We then compared the perecentages of MHC and sarcomeric alpha-actin expressions determined from 1) the transcriptional assays and 2) total isolated RNA (alpha-MHC: 90.1 +/- 4.8% (transcription), 93.0 +/- 4.7% (accumulation); beta-MHC: 9.9 +/- 4.8%, 7.0 +/- 4.7%; cardiac alpha-actin: 84.0 +/- 2.5%, 84.9 +/- 2.5%; skeletal alpha-actin: 16.1 +/- 2.5%, 15.0 +/- 2.5%). The results support the conclusion that the primary mechanisms controlling the accumulations of these gene products are transcriptional. Additionally, we show that an anti-sense mRNA showing strong homology or identity with the 5' end of the beta-MHC gene is transcribed in cardiac nuclei but not in hepatocyte nuclei.
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PMID:Cardiac expressions of alpha- and beta-myosin heavy chains and sarcomeric alpha-actins are regulated through transcriptional mechanisms. Results from nuclear run-on assays in isolated rat cardiac nuclei. 161 95

Progressive changes in myosin isozyme expression and in energy-generating enzyme activities were followed in the diaphragm and, for comparison, in axial and appendicular muscles of rats from 18 d gestation to maturity. Native myosins were characterized by pyrophosphate gel electrophoresis. Myosin heavy-chain (MHC) isozymes were measured with ELISA using monoclonal antibodies and were localized by immunocytochemistry. RNA transcripts for the MHCs were demonstrated on Northern blots and by RNase protection assays. Quantitative activities of malate dehydrogenase (MDH), beta-hydroxyacyl CoA dehydrogenase (beta OAC), 1-phosphofructokinase (PFK), lactate dehydrogenase (LDH), creatine kinase (CK), and adenylokinase (AK) were measured in muscle homogenates and in individual fibers by fluorometric pyridine nucleotide-dependent assays. Compared to limb muscles, expression of neonatal myosin in the diaphragm is precocious. Neonatal MHC mRNA is prominent in the diaphragm at 19 d gestation, and neonatal myosin is the major MHC isoform present at birth. Slow and fast IIa MHCs are also present at birth. Transcripts for IIa MHC are detectable in the diaphragm at 21 d gestation and are upregulated at birth. Comparable signal for IIa MHC mRNA is not found in the gastrocnemius until 10 d postpartum. Adult fast IIb MHC mRNA was detected only as a faint signal at 30-40 d in the diaphragm and then disappeared. Results indicate that a separate phenotype, the IIx type, matures late in diaphragmatic development. The activities of enzymes representing all of the major energy pathways are higher in the fetal diaphragm than in the fetal hindlimb muscles. For example, beta OAC had sixfold higher activity in the diaphragm than in the extensor digitorum longus (EDL) muscle at birth, activity in the diaphragm than in the extensor digitorum longus (EDL) muscle at birth.
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PMID:Metabolic and contractile protein expression in developing rat diaphragm muscle. 202 44

We have examined the transcriptional regulation of the rabbit myosin heavy chain (HC) beta gene by using DNA-mediated transfection experiments. To analyze the activity of the myosin HC beta promoter in a myogenic background, cultured myoblasts from 12-day-old chick embryonic breast muscle were transfected with a chimeric gene containing 781 base pairs of the promoter region fused to the gene for chloramphenicol acetyltransferase (CAT). As indicated by the transient expression of chloramphenicol acetyltransferase, the activity of the promoter in myoblast cultures increased at least 32-fold following differentiation and was selectively inhibited when myogenesis was blocked with 5-bromodeoxyuridine. Furthermore, RNase protection experiments showed that the in vivo myosin HC beta transcriptional initiation (or cap) site was utilized in the transfected skeletal muscle cells and also that the regulation of the exogenous promoter was similar to the induction of the endogenous skeletal alpha-actin gene. The results indicated that the exogenous promoter is regulated in a tissue- and stage-specific manner. By creating progressive 5' deletions of the promoter, we showed that only the region extending -294 base pairs upstream from the cap site is necessary for the muscle-specific expression. Linker-scanner mutagenesis of this region indicated that the positive regulation in differentiated skeletal muscle is mediated by at least two distinct elements within the 5'-flanking region of the myosin HC beta gene.
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PMID:Muscle-specific regulation of a transfected rabbit myosin heavy chain beta gene promoter. 256 93

The seco-steroid hormone 1,25-dihydroxyvitamin D3 is known to induce the expression of a calcium binding protein termed calbindin-D28K in a variety of target tissues. In order to comprehend the mechanism of induction we have cloned and sequenced the chicken calbindin-D28K gene. The gene spans some 18.5 kilobases (kb) of chromosomal DNA from the putative Cap site to the polyadenylation site of the 2.8 kb mRNA. It is split into 11 coding exons by 10 intervening sequences. The promoter region of this gene is markedly G + C-rich (60-80%) extending from -225 to +400. Within this region we find 70 CpG dinucleotides, four G-C boxes, and numerous known promoter regulatory signals. These putative regulatory signals include a TATA box (ATAAATA) at -30 and a CAT box (CCAAT) at -326. Ten additional variant CAT boxes are found in the upstream promoter region (-218 to -770) of this gene. Furthermore we have identified a glucocorticoid-like responsive element at -410 (TCTACACACTGTTCC) and this element overlaps a metal responsive element (TGCACTC) and a variant CAT box (CCAAAT) and juxtaposes an enhancer-like core element (AAATGGT) on its 3'-side. In addition, the calbindin-D28K promoter is composed of a variety of simple repeated sequences, some of which are components of putative regulatory signals. All splice junctions were found to conform to the GT-AG rule. A consensus sequence of the 5'-splice junction reads AG/GTAAG-TTATA. A consensus sequence of the 3'-splice site consists of two elements: a pyrimidine track (mainly T) followed by ACAG/G-T. A two-dimensional model of calbindin-D28K was constructed which projects the existence of 6 alpha-helix-loop-alpha-helix regions characteristic of calcium binding domains. The 3'-end of the gene consists of a single large (2039 base pair) uninterrupted exon, an organizational feature common to other members of the calcium binding protein gene family which include calmodulin, parvalbumin, Spec I, myosin light chains, etc. Another feature common to the gene family is the presence of the repeated sequence ATTT or TTTA located in the 3'-untranslated exons. These simple repeat sequences could be involved in regulating mRNA degradation by serving as a ribonuclease recognition signal.
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PMID:Molecular structure of the chicken vitamin D-induced calbindin-D28K gene reveals eleven exons, six Ca2+-binding domains, and numerous promoter regulatory elements. 296 15

Myosin prepared from tilapia (Serotherodon aureus) was complexed with 8-anilino-1-naphthalene sulfonate (ANS) and continuously heated at 1 degree C/min. A large increase in fluorescence was observed with a transition temperature of 34 degrees C. The effect of several salts on the transition temperature was tested. A plot based on the equation of E. E. Schrier and E. B. Schrier [(1967) J. Phys. Chem. 71, 1851-1860] gave a value of less than or equal to 500 cal/mol-deg for the change in enthalpy per residue due to exposure to solvent. The ratio of hydrophobic group to amide group exposure to solvent was intermediate compared with the ratio of RNase and gelatin. Fluorescence titrations yielded one high affinity site with a Kb of 2 X 10(6) M-1 and at least 200 low affinity sites with an average value of 1 X 10(5) M-1. The parameters did not change significantly with temperature. We propose that the increase in ANS fluorescence reflects changes in conformation of myosin as monitored by these low affinity sites, resulting in an increase in surface hydrophobicity and representing a small enthalpic change in the conformation of the myosin molecule. As a consequence, the change in conformation accelerates polymerization of myosin oligomers.
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PMID:The binding of 8-anilino-1-naphthalene sulfonate (ANS) to fish myosin and the effect of salts on the thermal transitions of fish myosin-ANS complex. 319 Feb 40


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