PubMed Health⌕ Search

Biomedical subjects

P J Farrell

Publications and source records attributed to P J Farrell.

107 records · Page 6Linked to original sources
PubMed1983

DNA sequence analysis of the EcoRI Dhet fragment of B95-8 Epstein-Barr virus containing the terminal repeat sequences.

An analysis of the approximately 12,440 base-pair sequence of the EcoRI Dhet fragment isolated from the circular episomal form of the B95-8 strain of Epstein-Barr virus is presented. This fragment contains the covalently joined ends of the intracellular episomal form of the molecule. In the viral capsid the DNA is linear and the joining is mediated via the terminal repeated DNA. Four copies of tandem repeated DNA were present in this clone, three with a repeat size of 538 and one of 523. The positions of a number of possible protein coding regions and transcription signals are discussed. In particular a possible spliced coding region for an approximately 45,000 Mr protein expressed in latently infected transformed cells is proposed. The predicted protein sequence contains hydrophobic regions separated by charged amino acids reminiscent of a membrane protein.

Animals↗
PubMed1982

Unrearranged immunoglobulin variable region genes have a functional promoter.

We have tested whether immunoglobulin light chain variable region genes are capable of directing initiation of transcription without undergoing the DNA rearrangement which creates a complete immunoglobulin gene. Two human Vk genes specifically initiated transcription in vitro at a site which is approximately 30 bases downstream of a TATA box and 20 bases upstream of the initiation codon. A Vk pseudogene which lacks a TATA box at an homologous position was not transcribed to a detectable extent in the in vitro system. One of the Vk genes was injected into Xenopus oocytes and it initiated transcription at precisely the same position as in the HeLa cell extract. It is suggested that the promoter which we have identified upstream of unrearranged Vk genes operates in lymphocytes after V-J joining has occurred to initiate transcription of light chain messenger RNA.

Animals↗
PubMed1980

Interferon, double-stranded RNA, and RNA degradation. Isolation of homogeneous pppA(2'p5'A)n-1 synthetase from Ehrlich ascites tumor cells.

pppA(2'p5'A)n-1 ((2'-5')(A)n) synthetase is one of the mediators of interferon action. On activation by double-stranded RNA, it converts ATP into (2'-5')(A)n; in turn, (2'-5')(A)n activates an endonuclease (RNase L) which cleaves single-stranded RNA. We report a simple procedure for the isolation of pure (2'-5')(A)n synthetase from interferon-treated Ehrlich ascites tumor cells. The procedure involves differential precipitation of the ribosomal salt wash fraction with ammonium sulfate and chromatography on DEAE-cellulose and CM-cellulose. The apparent molecular weight of the enzyme is 105,000 as determined by gel electrophoresis in sodium dodecyl sulfate and about 85,000 when determined by centrifugation through a glycerol gradient. The size range of the (2'-5')(A)n produced by the enzyme extends from the dimer to at least the pentadecamer.

2',5'-Oligoadenylate Synthetase↗
PubMed1978

Analysis of phosphorylation of protein synthesis initiation factor eIF-2 by two-dimensional gel electrophoresis.

We describe a method for examining the state of phosphorylation of initiation factor eIF-2 in reticulocyte lysates. The procedure involves incubation of the lysate with iodo[1-14C]acetate in 8.5 M urea, and fractionation of the labelled proteins by two-dimensional acrylamide gel electrophoresis. This approach has been used to show that haem deficiency, double-stranded RNA, and oxidised glutathione, which all inhibit the initiation of protein synthesis in an analogous manner, all cause a net increase in the level of phosphorylated eIF-2 in the complete lysate protein synthesis system.

Animals↗
PubMed1978

Interferon action: two distinct pathways for inhibition of protein synthesis by double-stranded RNA.

Double-stranded RNA inhibits protein synthesis in at least two ways. It activates a protein kinase that blocks peptide chain initiation by phosphorylating the peptide chain initiation factor eIF-2 and also activates an endonuclease that inactivates different mRNAs at different rates. The protein kinase and the endonuclease have been partially purified from interferon-treated Ehrlich ascites tumor cells. The 2',5'-oligoadenylates [pppA(2'p5'A)n], found found earlier to be mediators in the activation of the endonuclease by double-stranded RNA, are not mediators in the activation of the protein kinase by double-stranded RNA.

Adenine Nucleotides↗
PubMed1977

Phosphorylation of initiation factor elF-2 and the control of reticulocyte protein synthesis.

When rabbit reticulocyte lysates are incubated in the absence of hemin or in the presence of low concentrations of double-stranded RNA, the rate of initiation of protein synthesis is severely reduced after a lag period in which control rates are observed. This reduced initiation rate is due to inhibition of the binding of Methionyl-tRNAf to native 40S ribosomal subunits and is caused by a macromolecular inhibitor which is activated under these conditions. This paper shows that the inhibitors activated in these two situations appear to be different entities, but that in both cases, the inhibitor has an associated protein kinase activity which is highly selective for the small subunit of elF-2, the initiation factor which catalyzes binding of Methionyl-tRNAf to 40S subunits. We present several lines of evidence in support of the hypothesis that the phosphorylation of elF-2 by these kinases is basis of the control of initiation in lysates incubated under these conditions.

Adenosine Triphosphate↗
PubMedDate not supplied

Screening of transformed insect cell lines for recombinant protein production.

Nine insect cell lines were evaluated for their potential as host systems for recombinant protein production using a new expression vector permitting the continuous high-level expression of secreted glycoproteins by transformed insect cells (Farrell et al., 1998). As a means of preliminary screening, all nine insect cell lines were transfected with the green fluorescence protein. Growth in static and suspension culture was then examined as a further method of screening. On the basis of their transfection efficiencies and cell growth characteristics, five insect cell lines, Bm5, High Five, IPLB-LdFB, IZD-MB-0503, and Sf-21, were selected for stable transformation to produce granulocyte-macrophage colony-stimulating factor (GM-CSF). These five cell lines were stably transformed using an antibiotic resistance scheme and evaluated as a polyclonal population. Increasing the antibiotic concentration was found to cause not only a decrease in the specific growth rate but also an increase in the specific protein production rate and final GM-CSF concentration. The transformed High Five cells exhibited by far the greatest specific protein production rate of 5.1 x 10(-)(6) microgram/(cell.h), resulting in the highest final GM-CSF concentration of 22.8 mg/L when grown in static culture. One cloned High Five cell line produced a GM-CSF concentration of 46 mg/L in static culture and 27 mg/L in suspension culture.

Animals↗
PubMedDate not supplied

DNA sequence and expression of the B95-8 Epstein-Barr virus genome.

The complete (172,282 base pairs) nucleotide sequence of the B95-8 strain of Epstein-Barr virus has been established using the dideoxynucleotide/M13 sequencing procedure. Many RNA polymerase II promoters have been mapped and the mRNAs from these promoters have been assigned to the latent or early/late productive virus cycles. Likely protein-coding regions have been identified and three of these have been shown to encode a ribonucleotide reductase, a DNA polymerase and two surface glycoproteins.

Base Sequence↗