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:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reverse transcriptase activity of lymphadenopathy associated virus was assayed after exposure to various standard chemical disinfectants. 25% ethanol or 1% glutaraldehyde should prove sufficient to disinfect medical instruments, and 0.2% sodium hypochlorite for cleaning floors and benches. 0.1% formalin is too slow to be recommended.
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PMID:Inactivation of lymphadenopathy associated virus by chemical disinfectants. 620

Rotavirus gene products were examined, with the simian rotavirus SA11 as a model. The endogenous viral RNA-dependent RNA polymerase associated with single-shelled virus particles or with activated double-shelled particles was used to synthesize viral RNA transcripts. Sedimentation velocity sucrose gradient analysis of the RNA transcripts revealed four peaks at 9S, 12S, 14S, and 18S, whereas agarose gel electrophoresis under partially denaturing conditions revealed eight groups of RNA species ranging in molecular weight from 2 x 10(5) to 1.2 x 10(6). The transcripts synthesized in vitro were active in an mRNA-dependent cell-free translation system derived from rabbit reticulocytes. The transcripts directed the synthesis of 11 polypeptides that had molecular weights ranging from 125,000 to 20,000 when analyzed by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels. The products of in vitro translation were compared with polypeptides from purified virus and those synthesized in infected cells. Several of the polypeptides synthesized in vitro were designated as structural polypeptides by comparing the molecular weights determined by polyacrylamide gel electrophoresis analysis or by precipitation with hyperimmune serum prepared against purified virus. Three of the viral structural polypeptides (VP4, -5, and -5a) were not synthesized in vitro as primary gene products, demonstrating that processing must occur for the production of some structural polypeptides. Other in vitro-synthesized polypeptides were tentatively identified as either precursors to the viral glycoproteins or nonstructural polypeptides.
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PMID:In vitro transcription and translation of simian rotavirus SA11 gene products. 624 62

A template-dependent polyuridylic acid [poly(U)] polymerase has been isolated from BHK cells infected with foot-and-mouth disease virus (FMDV). Enzyme activity in a 20,000 x g supernatant of a cytoplasmic extract was concentrated by precipitation with 30 to 50% saturated ammonium sulfate. The poly(U) polymerase was freed of membranes by sodium dodecyl sulfate and 1,1,2-trichlorotrifluoroethane extraction, and RNA was removed by precipitation with 2 M LiCl. The solubilized poly(U) polymerase required polyadenylic acid as template complexed to an oligouridylic acid primer and Mg2+ for activity, but was inhibited by Mn2+. Antisera from animals infected with FMDV had previously been shown to inhibit the activity of FMDV RNA replicase complexed to the endogenous RNA template. The same antisera also inhibited the activity of poly(U) polymerase. Antisera depleted of antibody by absorption with the virus infection-associated antigen of FMDV no longer inhibited replicase and polymerase activities. The evidence suggests that FMDV RNA replicase, poly(U) polymerase, and the virus infection-associated antigen share a common protein.
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PMID:Isolation of a foot-and-mouth disease polyuridylic acid polymerase and its inhibition by antibody. 625 Dec 48

Effects of Ca2+ and Mg2+ on the "switch-on" of transcriptase function in reovirus intermediate subviral particles were examined. Switch-on in this system is triggered by K+ ions, whereas Na+ ions antagonize the effects of K+ ions. Once effected, switch-on is irreversible. In the absence of Ca2+ and Mg2+ ions, switch-on of transcriptase is effected by incubation at 37 degrees C in the presence of a particular ratio of K+/Na+ (total K+ plus Na+ being kept constant). Inclusion of Ca2+ in the activation step lowers the ratio that triggers the switch-on event. This indicates that Ca2+ destabilizes the switched-off state of the transcriptase. Inclusions of Mg2+ ions in the activation step raises the K+/Na+ ratio necessary to trigger switch-on. Thus Mg2+ tends to stabilize the switched-off state of the transcriptase to the triggering action of K+ ions. Inclusion of both Ca2+ and Mg2+ together during the activation step results in mutual inhibition of the effects expected from each divalent cation alone. These results indicate that switch-on of transcriptase function, which is triggered by K+ ions, can be modulated by interactions involving the major physiological cations (Na+, K+, Mg2+, Ca2+).
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PMID:Effects of Ca2+ and Mg2+ on the switch-on of transcriptase function in reovirus in vitro. 642 61

Mounting experimental evidence suggests that the TAT protein, released from human immunodeficiency virus-1 (HIV-1)-infected inflammatory cells, may genetically reprogram targeted cells within a localized environment to develop highly vascularized tumors of mesenchymal origin. The fibroblast growth factor (FGF) family of polypeptides has gained general acceptance as initiators of angiogenesis and functions as potent mitogens for mesoderm-derived cells. To evaluate a potential biological relationship between TAT and acidic FGF (FGF-1), primary murine embryonic fibroblasts either were transfected with the viral transactivator or were transduced (retrovirally mediated) with a secreted, chimeric form of the human polypeptide growth factor, human stomach tumor/Kaposi's sarcoma (hst/KS)FGF-1. Reverse transcriptase-polymerase chain reaction, Western blotting, in situ immunohistochemical, heparin affinity, DNA synthesis, and transient transfection techniques were used to confirm expression, localization, and functionality of the transgenes. Both transfected and transduced cells constitutively expressing either TAT or (hst/KS)FGF-1 adopted a transformed phenotype, maintained aggressive growth behavior, and demonstrated both induction of FGF-specific phosphotyrosyl proteins and nuclear association of FGF-1 and FGF-1 receptor. Increased levels of endogenous, murine FGF-1 mRNA (reverse transcriptase-polymerase chain reaction) and protein (immunoblot analysis) were apparent in both (hst/KS)FGF-1- and TAT-transformed cells. Medium conditioned by (hst/KS)FGF-1-transduced cells contained steady-state levels of biologically active FGF-1 which exhibited a representative molecular weight. Limited sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the conditioned medium from TAT-transformed cells demonstrated the appearance of FGF-1 as latent, high molecular weight complexes requiring reducing agents to activate full biological activity. Collectively, these results suggest that TAT induces the expression and secretion of FGF-1, which may be potentially relevant to the pathophysiological development of AIDS-Kaposi's sarcoma.
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PMID:The HIV-1 TAT protein induces the expression and extracellular appearance of acidic fibroblast growth factor. 754 39

The basophilic leucaemia cell line RBL-2H3 exhibits a robust inwardly rectifying potassium current, IKIR, which is likely to be modulated by G proteins. We examined the physiological and molecular properties of this KIR conductance to define the nature of the underlying channel species. The macroscopic conductance revealed characteristics typical of classical K+ inward rectifiers of the IRK type. Channel gating was rapid, first order (tau approximately 1 ms at -100 mV) and steeply voltage dependent. Both activation potential and slope conductance were dependent on extracellular K+ concentration ([K+]o) and inward rectification persisted in the absence of internal Mg2+. The current was susceptible to a concentration- and voltage-dependent block by extracellular Na+, Cs+ and Ba2+. Initial IKIR whole-cell amplitudes as well as current rundown were dependent on the presence of 1 mM internal ATP. Perfusion of intracellular guanosine 5'-Q-(3-thiotriphosphate) (GTP[gamma S]) suppressed IKIR with an average half-time of decline of approximately 400 s. It was demonstrated that the dominant IRK-type 25 pS conductance channel was indeed suppressed by 100 microM preloaded GTP[gamma S]. Reverse transcriptase-polymerase chain reactions (RT-PCR) with RBL cell poly(A)+ RNA identified a full length K+ inward rectifier with 94% base pair homology to the recently cloned mouse IRK1 channel. It is concluded that RBL cells express a classical voltage-dependent IRK-type K+ inward rectifier RBL-IRK1 which is negatively controlled by G proteins.
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PMID:Physiological and molecular characterization of an IRK-type inward rectifier K+ channel in a tumour mast cell line. 760 35

Bovine herpesvirus 1 (BHV-1) establishes a latent infection in sensory ganglionic neurons of infected animals. Expression of latency-related (LR) gene products is controlled by a 980-bp fragment (LR promoter). DNA sequence analysis revealed that two major open reading frames (ORFs) are in the LR gene. Antibodies directed against both ORFs were generated in rabbits by using synthetic peptides. Antibody P2, which is directed to sequences near the amino terminus of ORF 2, recognized a 41-kDa protein in lytically infected cells, suggesting that ORF 2 encodes a protein. When the LR gene was inserted into a mammalian expression vector and subsequently transfected into COS-7 cells, a 41-kDa protein was detected by use of silver-stained sodium dodecyl sulfate-polyacrylamide gels and by the P2 antibody. In contrast, this protein was not detected in mock-transfected cells. Deletion of DNA sequences containing ORF 2 blocked synthesis of the 41-kDa protein in COS-7 cells. Reverse transcriptase-mediated PCRs indicated that splicing occurs near the C terminus of ORF 2. Further studies indicated that LR RNA was alternatively spliced in latently infected cattle and that a fraction of LR RNA was poly(A)+. Taken together, these studies suggested that a spliced LR transcript has the potential to encode a 41-kDa protein.
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PMID:Identification of gene products encoded by the latency-related gene of bovine herpesvirus 1. 763 78

Using a combination of polymerase chain reaction and genomic library screening we have cloned a human gene for a subtype of the somatostatin (SST) receptor (SSTR) termed human SSTR5 (hSSTR5), which is located on chromosome 16. The predicted amino acid sequence of hSSTR5 displays 75% sequence identity with a recently identified rat SSTR [Mol. Pharmacol. 42:939-946 (1992)], suggesting that it is the human homologue of this receptor. hSSTR5 consists of a 363-residue polypeptide exhibiting a putative seven-transmembrane domain topology typical of G protein-coupled receptors. The receptor displays considerable sequence identity to hSSTR1 (42%), hSSTR2 (48%), hSSTR3 (47%), and hSSTR4 (46%). Membranes prepared from COS-7 cells transiently expressing the hSSTR5 gene bound 125I-Leu8,D-Trp22,Tyr25-SST-28 (125I-LTT-SST-28) with high affinity and in a saturable manner. SST-14, SST-28, and various synthetic SST peptide agonists produced dose-dependent inhibition of radioligand binding with the following rank order of potency: LTT-SST-28 > SST-28 > D-Trp8-SST-14 > SST-14 approximately RC-160 approximately BIM 23014 > MK-678 > SMS 201-995. hSSTR5 bound SST-28 with a 12.6-fold greater affinity (Ki = 0.19 nM), compared with SST-14 (Ki = 2.24 nM), indicating that the receptor is SST-28 selective. Addition of GTP, guanosine-5'-O-(3-thio)triphosphate, Na+ ions, or pertusis toxin greatly reduced 125I-LTT-SST-28 binding, thereby indicating that hSSTR5 is coupled to pertussis toxin-sensitive G proteins. Both SST-14 and SST-28 displayed dose-dependent inhibition of forskolin-stimulated cAMP accumulation, consistent with functional coupling of the receptor to adenylyl cyclase inhibition. Northern blot analysis of SSTR5 mRNA revealed a 2.4-kilobase transcript in normal rat pituitary and GH3 rat pituitary tumor cells and a 4.0-kilobase transcript in normal human pituitary. Reverse transcriptase polymerase chain reaction revealed expression of the hSSTR gene in fetal human pituitary and hypothalamus but not in human cerebral cortex. In situ hybridization of the rat pituitary showed that SSTR5 mRNA is selectively localized in the anterior lobe. SSTR5 mRNA was not expressed in four human pituitary tumors (somatotroph adenoma, prolactinoma, and chromophobe adenomas) or in a human insulinoma. Although hSSTR5 displays approximately 75% sequence identity with rat SSTR5, the two receptors display significantly different pharmacological profiles, especially with respect to their binding affinities for the SST analogue SMS 201-995.
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PMID:Molecular cloning, functional characterization, and chromosomal localization of a human somatostatin receptor (somatostatin receptor type 5) with preferential affinity for somatostatin-28. 790 5

The capsid protein (CP) of alfalfa mosaic virus (AIMV) is required for viral replication when susceptible plants are inoculated with purified viral genomic RNA. The discovery of AIMV CP in the zinc activated RNA-dependent RNA polymerase complex prompted our further investigation of AIMV virions and the potential involvement of AIMV CP in metal binding. AIMV CP, isolated from nucleoprotein components, fractionated into four distinct ionic species when purified by cation exchange fast protein liquid chromatography. The CP existed as zinc complexed homodimers, metal-free homodimers, and two forms of proteolyzed heterodimers, as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gel filtration chromatography, amino-terminal sequencing, and atomic absorption spectroscopy. Although the relative amounts of proteolyzed heterodimers varied, the ratio of zinc complexed homodimers to metal-free homodimers (1:10) was constant between virus and protein isolations for the strains 425 and WISC14. Purified metal-free and zinc-complexed homodimers could be interconverted in vitro by incubation with zinc chloride or with the metal chelator, sodium diethyldithiocarbamate (NaDDC). The potential role of zinc in AIMV nucleoprotein structure and infectivity was investigated by treatment of the virions with NaDDC. Electron microscopy and sucrose density gradient studies failed to detect any gross structural changes for zinc depleted virus; however, a decrease in infectivity was observed with local lesion leaf assays, suggesting a functional role for zinc in viral replication.
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PMID:A chromatographic analysis of capsid protein isolated from alfalfa mosaic virus: zinc binding and proteolysis cause distinct charge heterogeneity. 794 57

A terminal adenylyl transferase (TATase) activity has been identified in preparations of purified poliovirus RNA-dependent RNA polymerase (3Dpol). Highly purified 3Dpol is capable of adding [32P]AMP to the 3' ends of chemically synthesized 12-nucleotide (nt)-long RNAs. The purified 52-kDa polypeptide, isolated after sodium dodecyl sulfate-polyacrylamide gel electrophoresis and renatured, retained the TATase activity. Two 3Dpol mutants, purified from Escherichia coli expression systems, displayed no detectable polymerase activity and were unable to catalyze TATase activity. Likewise, extracts from the parental E. coli strain that harbored no expression plasmid were unable to catalyze formation of the TATase products. With the RNA oligonucleotide 5'-CCUGCUUUUGCA-3' used as an acceptor, the products formed by wild-type 3Dpol were 9 and 18 nt longer than the 12-nt oligomer. GTP, CTP, and UTP did not serve as substrates for transfer to this RNA, either by themselves or when all deoxynucleoside triphosphates were present in the reaction. Results from kinetic and stoichiometric analyses suggest that the reaction is catalytic and shows substrate and enzyme dependence. The 3'-terminal 13 nt of poliovirus minus-strand RNA also served as an acceptor for TATase activity, raising the possibility that this activity functions in poliovirus RNA replication. The efficiency of utilization and the nature of the products formed during the reaction were dependent on the acceptor RNA.
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PMID:Identification of terminal adenylyl transferase activity of the poliovirus polymerase 3Dpol. 805 62


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