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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The divergent, muscle-specific allele of the chicken calmodulin gene contains no intervening sequences and apparently was produced by a reverse transcriptase-mediated event. The nucleotide and deduced amino acid sequences of this gene were compared with nucleotide and amino acid sequence data of other known calmodulin genes in order to investigate its evolutionary history. These comparisons, as well as the CpG dinucleotide content, support the conclusion that this highly divergent chicken calmodulin gene did not exist for any significant period of times as a pseudogene and suggest plausible alternative genetic histories. The most parsimonious history involves the viral import of a very old foreign gene of high CpG content.
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PMID:Possible origin of a calmodulin gene that lacks intervening sequences. 347 Jul 46

Exposure in vitro of various mammalian retroviruses to the chelating agents EDTA or EGTA in millimolar concentrations resulted in partial disintegration of viral membranes as measured by accessibility or even release of reverse transcriptase, an internal viral protein, without any other treatment usually required. Among the viruses responding to chelators were mammalian type C viruses, primate type D viruses and bovine leukemia virus. The effect was dose-dependent. The avian type C virus AMV, however, was found to be not susceptible to the agents. Rauscher mouse leukemia virus treated in vitro with EDTA or EGTA showed reduced infectivity in mice. The results are considered as evidence for some association of divalent cations with membranes of mammalian retroviruses. The disintegrating activity of EGTA suggests that Ca2+ is an integral constituent of viruses but Mg2+ may also be involved. These cations seem to be responsible for maintaining integrity of retroviral membranes which, after chelation of ions, are either disrupted or become permeable for the exogenous template of reverse transcriptase. In addition, the disintegrating activity of trifluoperazine may indicate that a calmodulin-like protein occurs in retroviral membranes.
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PMID:Disintegration of retroviruses by chelating agents. 681 93

Calmodulin mRNA has been partially purified from a total nucleic acid extract of the electroplax of Electrophorus electricus by oligo(dT)-cellulose chromatography and sucrose gradient centrifugation. A 9- to 10S fraction was determined to contain 39% calmodulin mRNA by translation in a reticulocyte lysate followed by immunoprecipitation with antibodies to calmodulin. Double-stranded cDNA was synthesized from the RNA fraction by using reverse transcriptase from avian myeloblastosis virus. The double-stranded cDNA was joined to pBR322 linearized by restriction endonuclease Pst I and used to transform Escherichia coli RRI. DNAs from 60 tetracycline-resistant cloned hybridized to [32P]cDNA synthesized from the partially purified calmodulin mRNA fraction. By direct DNA sequence analysis, one of these clones, pCM109, was shown to contain calmodulin-specific sequences corresponding to amino acid residues 93--148 of calmodulin or approximately 38% of the peptide-coding region of the calmodulin structural gene sequence. pCM109 was hybridized to DNA isolated from three vertebrate and one plant species by the procedure of Southern. Positive hybridization bands were noted regardless of the DNA source. These data suggest thaat calmodulin gene sequences are evolutionarily conserved, as has been shown to be the case for the primary amino acid sequence.
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PMID:A cloned calmodulin structural gene probe is complementary to DNA sequences from diverse species. 694 Dec 92

Nitric oxide (NO) which is produced by activation of Ca2+/calmodulin-dependent NO synthase is known to induce neuronal damage. We examined the effects of 3'-azido-2',3'-dideoxythymidine (AZT, a reverse transcriptase inhibitor), pentamidine (a therapeutic drug for Pneumocystis carinii pneumonia) and calmodulin antagonists such as trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) on NO synthase activation. Although AZT had no effect on the activity of constitutive neuronal NO synthase, pentamidine inhibited the activation of neuronal NO synthase as did trifluoperazine and W-7. The inhibition by pentamidine was prevented by the addition of purified calmodulin. In addition, pentamidine inhibited calmodulin-dependent activation of neuronal NO synthase purified from rat cerebellum. From these results, it is suggested that pentamidine inhibits the neuronal NO synthase activation by probably acting as a calmodulin antagonist.
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PMID:Inhibition of constitutive nitric oxide synthase in the brain by pentamidine, a calmodulin antagonist. 754 7

There is evidence for a role for calcium/calmodulin-dependent protein phosphorylation in regulation of insulin secretion but the molecular nature of the kinase(s) responsible is unknown. In this study, the screening of a neonatal rat islet cDNA library resulted in the isolation of a 2 kb clone that was 99% homologous to the beta' isoform of calcium/calmodulin-dependent protein kinase II. The predicted 589 amino acid sequence with a calculated mass of 64,976 Da contained a 24 amino acid deletion in addition to the 15 amino acid deletion that differentiates the beta' from the beta isoform, and included an 86 amino acid novel domain consisting of a tandem repeat of proline-rich residues. The expression of this new isoform of calcium/calmodulin-dependent protein kinase II (beta 3) was confirmed in beta-cell lines and testis by DNA amplification of the sequence encoding the inserted domain by reverse transcriptase-polymerase chain reaction, followed by Southern analysis.
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PMID:A novel pancreatic beta-cell isoform of calcium/calmodulin-dependent protein kinase II (beta 3 isoform) contains a proline-rich tandem repeat in the association domain. 782 22

In order to obtain the 5' ends of the three mouse calmodulin (CaM) cDNAs, we modified the standard 5' RACE (rapid amplification of cDNA ends) method to use degenerate synthetic oligodeoxyribonucleotides to prime cDNA synthesis of all three CaM mRNAs. In this modified method, the degenerate primers were annealed to mRNAs in an incubation step prior to the reverse transcription reaction. Separating the annealing step from the reverse transcription reaction allowed for greater stringency by using higher temperatures than could be tolerated if the reverse transcriptase were present. Annealing was also done with lower primer concentration and was driven by a longer incubation time. After the annealing step, cDNA synthesis was initiated by diluting the annealing mixture into a 42 degrees C buffer with reverse transcriptase. The synthesized cDNA was poly(dA)-tailed to allow PCR amplification of the first-strand cDNA with an anchor-dT17 primer and the degenerate primers. The CaM cDNAs were evident after this PCR. A second PCR, with nested gene-specific primers, was used to isolate the individual CaM cDNAs from the products of the first PCR. Three distinct CaM cDNAs were cloned and sequenced. By comparison of the 5' untranslated sequences between the mouse CaM DNAs and rat CaM cDNAs, the corresponding homologs were assigned. The results suggest that application of this modified RACE method could improve the success of isolating specific cDNAs in cases where use of a nested primer is not possible or when amino-acid sequence information is available and only degenerate primers can be designed for cloning cDNAs by the 5'-RACE method.
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PMID:Three different calmodulin-encoding cDNAs isolated by a modified 5'-RACE using degenerate oligodeoxyribonucleotides. 782 84

A cDNA encoding the regulatory subunit of Ca2+/calmodulin-dependent protein phosphatase, calcineurin B (CNB), was isolated from a rat testis cDNA library. It differs from the cDNA obtained from a rat brain cDNA library by an addition of 138 base pairs in the coding region. The codon of the clone from a testis library corresponding to the initiation codon of the clone from a brain library is not ATG but AAG, 5'-noncoding regions of these cDNAs are also different. The addition in the coding region results in the gain of 46 amino acids at the N-terminus. These findings suggest that two distinct isoforms of CNB alpha are derived from the same gene through a process involving alternative utilization of two promoters. We designate the brain type isoform as CNB alpha 1 and the longer isoform as CNB alpha 2. Northern blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR) followed by Southern blot analysis suggest that CNB alpha 2 is specifically expressed in the testis, and its expression is developmentally regulated.
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PMID:cDNA cloning of an alternatively spliced isoform of the regulatory subunit of Ca2+/calmodulin-dependent protein phosphatase (calcineurin B alpha 2). 811 Aug 31

Organelles in the axoplasm from the squid giant axon move along exogenous actin filaments toward their barbed ends. An approximately 235-kDa protein, the only band recognized by a pan-myosin antibody in Western blots of isolated axoplasmic organelles, has been previously proposed to be a motor for these movements. Here, we purify this approximately 235-kDa protein (p235) from axoplasm and demonstrate that it is a myosin, because it is recognized by a pan-myosin antibody and has an actin-activated Mg-ATPase activity per mg of protein 40-fold higher than that of axoplasm. By low-angle rotary shadowing, p235 differs from myosin II and it does not form bipolar filaments in low salt. The amino acid sequence of a 17-kDa protein that copurifies with p235 shows that it is a squid optic lobe calcium-binding protein, which is more similar by amino acid sequence to calmodulin (69% identity) than to the light chains of myosin II (33% identity). A polyclonal antibody to this light chain was raised by using a synthetic peptide representing the calcium binding domain least similar to calmodulin. We then cloned this light chain by reverse transcriptase-PCR and showed that this antibody recognizes the bacterially expressed protein but not brain calmodulin. In Western blots of sucrose gradient fractions, the 17-kDa protein is found in the organelle fraction, suggesting that it is a light chain of the p235 myosin that is also associated with organelles.
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PMID:An axoplasmic myosin with a calmodulin-like light chain. 865 Feb 20

We used differential display of mRNA, a method based on reverse transcriptase-PCR, to identify genes whose expression increases in response to acoustic trauma in the chick basilar papilla. Identifying these genes would provide insight into processes involved in repair of the damaged epithelium or in hair cell regeneration. We compared mRNA from the basilar papilla of normal chicks, from chicks exposed to an octave band noise (center frequency: 1.5 kHz) presented at 118 dB for 6 h, and from chicks exposed to noise and allowed to recover for 2 days. Thus far, we have identified 70 bands that appear to be differentially displayed on DNA sequencing gels; approximately 40 of these bands have been subcloned and sequenced. DNA sequences were compared with sequences in the GenBank database to identify genes with significant (70-85%) sequence identity to known genes. Chick cDNAs identified included: the parathyroid hormone-related protein, an immediate early gene; the delta-subunit of the neuronal-specific Ca2+/calmodulin-regulated protein kinase II; and the GTP-binding protein CDC42, a member of the ras superfamily of G proteins. A fourth cDNA had 84% sequence identity to an uncharacterized human cDNA (expressed sequence tag), indicating that this is a novel gene. Slot-blot hybridization analysis of these cDNAs probed with labeled DNA generated from mRNA from each experimental group indicated higher levels of mRNA for each of these four genes after noise exposure. These results indicate the potential involvement of both Ca2+/calmodulin-mediated signaling and GTPase cascades in the response to noise damage and during hair cell regeneration in the chick basilar papilla.
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PMID:Identification of genes expressed after noise exposure in the chick basilar papilla. 881 3

The French paradox is a dietary anomaly which has focused attention on the Mediterranean diet. Epidemiological studies revealed that this diet, replete in flavonoid-rich foods (Allium and Brassica vegetables, and red wine), correlated with the increased longevity and decreased incidence of cardiovascular disease seen in these populations. The most frequently studied flavonoid, quercetin, has been shown to have biological properties consistent with its sparing effect on the cardiovascular system. Quercetin and other flavonoids have been shown to modify eicosanoid biosynthesis (antiprostanoid and anti-inflammatory responses), protect low-density lipoprotein from oxidation (prevent atherosclerotic plaque formation), prevent platelet aggregation (antithrombic effects), and promote relaxation of cardiovascular smooth muscle (antihypertensive, antiarrhythmic effects). In addition, flavonoids have been shown to have antiviral and carcinostatic properties. However, flavonoids are poorly absorbed from the gut and are subject to degradation by intestinal micro-organisms. The amount of quercetin that remains biologically available may not be of sufficient concentration, theoretically, to explain the beneficial effects seen with the Mediterranean diet. The role of flavonoids may transcend their presence in food. The activity of flavonoids as inhibitors of reverse transcriptase suggests a place for these compounds in the control of retrovirus infections, such as acquired immunodeficiency syndrome (AIDS). In addition to specific effects, the broad-modulating effects of flavonoids as antioxidants, inhibitors of ubiquitous enzymes (ornithine carboxylase, protein kinase, calmodulin), and promoters of vasodilatation and platelet disaggregation can serve as starting material for drug development programmes.
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PMID:Review of the biology of Quercetin and related bioflavonoids. 884 3


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