Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A pBR322-derived expression vector, plasmid pKD1, was constructed containing the strong leftward promoter (pL) of bacteriophage lambda, the ribosome-binding site (RBS) of the cII gene of lambda, and a unique downstream NdeI restriction site for construction of an ATG initiation codon. The section of the pol gene of Moloney murine leukemia virus (M-MLV) that codes for reverse transcriptase (RT) was cloned into the NdeI site of this vector generating the plasmid pRT103. Upon thermal induction, enzymatically active RT was expressed in Escherichia coli [pRT103]. The identity of this activity was confirmed by its template specificity and its sensitivity to inhibition by immunoglobulin G (IgG) prepared against authentic murine RT. RT represented 20% of the newly synthesized protein in these cells 20 min after induction.
 ...
PMID:Cloning and overexpression of Moloney murine leukemia virus reverse transcriptase in Escherichia coli. 241 39

A series of point mutations in the P30 domain of the Moloney murine leukemia virus gag gene was generated by bisulfite treatment of heteroduplex DNAs containing a single-stranded region in the gag gene. One virus bearing such a mutation exhibited a coordinate defect in gag and pol function, and was similar to previously described deletion mutants with alterations in this gene. One mutant virus displayed a different phenotype: it could assemble virion particles and provide pol function, but the particles were defective in the early stages of infection. The continued concordance of the mutants' failure or ability to both assemble virions and provide pol lends further support to the proposal that similar parts of the gag gene are required for these two processes.
 ...
PMID:Point mutations in the P30 domain of the gag gene of Moloney murine leukemia virus. 241 2

The NH2-terminal amino acid sequence of Moloney murine leukemia virus reverse transcriptase was determined to be Thr-Leu-Asn-Ile-Glu-Asp-Glu-Tyr-Arg-Leu-His-Glu-. The comparison of the amino acid analysis data obtained after carboxypeptidase Y digestion with the published nucleotide sequence (T. M. Shinnick, R. A. Lerner, and J. G. Sutcliffe, Nature (London) 293, 543-548, 1981) led to the conclusion that the COOH-terminus is Leu coded by CTC in nucleotide positions 4608-4610, and the tentative COOH-terminal sequence is Pro-Asp-Thr-Ser-Thr-Leu-Leu-OH. In light of these and previously reported results the complexity and map order of the pol gene are discussed.
 ...
PMID:Amino- and carboxyl-terminal sequence of Moloney murine leukemia virus reverse transcriptase. 241 14

In the absence of infectious virus, strains of mice express polyadenylated RNA transcripts homologous to the genome of murine leukemia virus. In addition to transcripts consistent with full-length and spliced env retroviral RNAs, several unique RNA species which lack the env sequence accumulate in a tissue-specific manner. These RNA species are presumed to be transcribed from endogenous retroviral sequences that constitute the bulk of the murine leukemia virus-related sequences in the murine genome. To determine the relationship of these RNA transcripts to infectious murine leukemia virus and the precise structural basis of the heterogeneity observed for the env-lacking transcripts, we isolated and sequenced cDNA recombinants representing the RNAs expressed in strain 129 GIX+ mice. Comparisons of the nucleotide sequences demonstrated that the endogenous retroviral transcripts differed in pol, p15E, and R-peptide regions by single nucleotide changes. In contrast, the gp70-coding regions of two cDNA clones derived from epididymis and liver were completely homologous over a 599-nucleotide overlapping sequence. The structures of env-lacking transcripts were examined in two independent cDNA clones, and each was found to contain a different deletion that was potentially mediated by seven-base pair direct repeats in the intact sequence. The extensive sequence homology between cDNAs allowed construction of a cumulative sequence map of the 3' end of an intact endogenous retroviral transcript. A comparison of this sequence with infectious ecotropic and mink cell focus-forming viruses revealed that the endogenous transcripts are highly homologous with the substituted portions of leukemogenic mink cell focus-forming viruses and therefore further define the boundaries of recombination required to generate these viruses.
 ...
PMID:Normal expression of polymorphic endogenous retroviral RNA containing segments identical to mink cell focus-forming virus. 241 14

Five recombinant DNA clones of endogenous feline leukemia virus-related DNA sequences were isolated by screening a lambda phage genomic library of cat placental DNA with a probe specific to the gag-pol region of infectious feline leukemia virus. The clones containing retroviral long terminal repeat-like sequences demonstrated the existence of different size classes of endogenous elements in the cat genome, including those of nearly full length in which the gag region is heterogeneous but all of pol and most of env are highly conserved. Other size classes included elements with major deletions in gag or pol. A genomic DNA analysis suggested that the majority of endogenous elements were close to full length in size and that the highly truncated sequences which we described previously (Soe et al., J. Virol. 46:829-840, 1983) represented only a subset of the elements present. A restriction analysis of genomic DNA suggested a high degree of conservation in pol and the 5' portion of env among the various endogenous sequences present in the cat genome. We also found by using DNA transfection that while all of the endogenous clones were noninfectious, there was differential expression of the elements which we examined. These findings correlate with the subgenomic expression of endogenous feline leukemia virus sequences in cat placental tissue.
 ...
PMID:Molecular analysis of several classes of endogenous feline leukemia virus elements. 241 15

The complete nucleotide sequence of 297, a Drosophila copia-like transposable element, was determined and compared with those of other similar Drosophila elements and mammalian retrovirus proviruses. It was found that 297 contains three long open reading frames, comparable in sizes and locations with gag, pol, and env genes in the proviruses of replication-competent retroviruses in vertebrates. The first and second open reading frames of 297 exhibit sequence homologies to gag and pol, respectively, of Moloney murine leukaemia virus. In particular, as with 17.6, another Drosophila copia-like element, the second open reading frame of 297 was shown to be very similar in its entire organization to the retroviral pol gene and to consist of three enzymatic domains. By contrast, no appreciable homology was found between the third open reading frame of 297 and the retroviral env gene. It is also suggested that 297 and 17.6 are a peculiar pair of copia-like elements recently diverged from a common progenitor.
 ...
PMID:Complete nucleotide sequence and genome organization of a Drosophila transposable genetic element, 297. 241 39

The nucleotide sequence of the internal region of a Drosophila retrotransposon. 412, was determined. The genome of 412 was found to consist of two long open-reading frames (ORFs 1 and 2), an unusually long putative leader region and long terminal repeats (LTRs). As with 17.6, 297 and gypsy, ORFs 1 and 2 slightly overlap each other and are out of phase by +2. ORF2 includes the nucleotide sequences coding for the putative protease, reverse transcriptase and integrase, and is similar in entire organization to the pol gene of Moloney murine leukaemia virus. In spite of the difference in insertion specificity, integrase, an enzyme presumably responsible for insertion, was found to be similar in amino acid sequence to the counterparts of 17.6, 297 and gypsy. There is no ORF in 412 which corresponds to retroviral env or ORF3s of 17.6 and 297. Analysis of 412 transcripts suggested that 412 LTR is composed of U3, R and U5. The gene for a potential primer tRNA for putative reverse transcription of 412 was also surveyed and the 3'-terminal 15 nucleotides of a putative arginine tRNA were found to be exactly complementary to the putative primer-binding site of 412.
 ...
PMID:Nucleotide sequence characterization of a Drosophila retrotransposon, 412. 242 8

Portions of the pol gene of Moloney murine leukemia virus (MuLV) were expressed as fusion proteins in Escherichia coli, and the purified proteins were used to elicit antibodies in Escherichia coli, and the purified proteins were used to elicit antibodies in rabbits. The sera were used to examine the mature pol gene products contained in virion particles and identified the reverse transcriptase and a second protein, P46pol, encoded by the 3' portion of the gene. The P46 protein was not phosphorylated and was present at the same molar abundance as the reverse transcriptase. The sera were also used to detect the Pr200gag-pol intracellular precursor protein and to analyze its processing to the mature forms. The proteins formed by several Moloney MuLV mutants were analyzed. Further tests revealed cross-reactivity with Friend MuLV and feline leukemia virus proteins, but not with avian retrovirus proteins.
 ...
PMID:Analysis of retroviral pol gene products with antisera raised against fusion proteins produced in Escherichia coli. 242 63

We have cloned and expressed in Escherichia coli a section of the Moloney murine leukemia virus (Mo-MLV) pol gene which includes the entire coding region of mature reverse transcriptase (RT) plus 284 additional base pairs 3' to the coding region (Kotewicz et al., 1985). To prepare cloned Mo-MLV RT as close as possible to authentic RT in structure and activity, the universal terminator sequence GC(TTAA)3GC was introduced at a number of positions inside and outside the RT coding region within 200 nucleotides of its 3' end. The level of RT activity expressed from these constructs varied sevenfold. This variation was found to be directly related to the stability of the RT protein products in the E. coli K-12 strain K802; half-lives varied from 2 to 35 min. The stability of most of the RT proteins was not increased in E. coli K802 lon- cells, with the exception of two, whose half-lives were increased by a factor of two.
 ...
PMID:Influence on stability in Escherichia coli of the carboxy-terminal structure of cloned Moloney murine leukemia virus reverse transcriptase. 242 93

The organization of the murine leukemia virus (MuLV) pol gene was investigated by expressing molecular clones containing AKR MuLV reverse transcriptase or endonuclease or both gene segments in Escherichia coli and generating specific antisera against the expressed bacterial proteins. Reaction of these antisera with detergent-disrupted virus precipitated an 80-kilodalton (kDa) protein, the MuLV reverse transcriptase, and a 46-kDa protein which we believe is the viral endonuclease. A third (50-kDa) protein, related to reverse transcriptase, was also precipitated. Bacterial extracts of clones expressing reverse transcriptase and endonuclease sequences competed with the viral 80- and 46-kDa proteins, respectively. These results demonstrate that the antisera are specific for viral reverse transcriptase and endonuclease. Immunoprecipitation of AKR MuLV with antisera prepared against a bacterial protein containing only endonuclease sequences led to the observation that reverse transcriptase and endonuclease can be associated as a complex involving a disulfide bond(s).
 ...
PMID:Murine leukemia virus pol gene products: analysis with antisera generated against reverse transcriptase and endonuclease fusion proteins expressed in Escherichia coli. 242 47


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