The publication data currently available has been vetted by Vanderbilt faculty, staff, administrators and trainees. The data itself is retrieved directly from NCBI's PubMed and is automatically updated on a weekly basis to ensure accuracy and completeness.
If you have any questions or comments, please contact us.
Two mutants were constructed to explore the functions of the sequences at the end of the S terminus of pseudorabies virus (PrV). In mutant vYa, 17 bp from the internal inverted repeat, as well as adjacent sequences from the L component, were deleted. In mutant v135/9, 143 bp from the internal inverted repeat (including sequences with homology to the pac-1 site of herpes simplex virus), as well as adjacent sequences from the L component, were deleted. Our aim in constructing these mutants was to ascertain whether equalization of the terminal regions of the S component would occur, whether genome termini that lack either the terminal 17 or 143 bp would be generated as a result of equalization of the repeats (thereby identifying the terminal nucleotides that may include cleavage signals), and whether inversion of the S component would occur (thereby ascertaining the importance of the deleted sequences in this process). The results obtained show the following (i) The removal of the terminal 17 or 143 bp of the internal S component, including the sequences with homology to the pac-1 site, does not affect the inversion of the Us. (ii) The equalization of both the vYa and the v135/9 inverted repeats occurs at high frequency, the terminal repeats being converted and becoming similar to the mutated internal inverted repeat. (iii) Mutants in which the 17 terminal base pairs (vYa) have been replaced by unrelated sequences are viable. However, the 143 terminal base pairs appear to be essential to virus survival; concatemeric v135/9 DNA with equalized, mutant-type, inverted repeats accumulates, but mature virions with such equalized repeats are not generated at high frequency. Since concatemeric DNA missing the 143 bp at both ends of the S component is not cleaved, the terminal 143 bp that include the sequences with homology to the pac-1 site are necessary for efficient cleavage. (iv) v135/9 intracellular DNA is composed mainly of arrays in which one S component (with two equalized inverted repeats both having the deletion) is bracketed by two L components in opposite orientations and in which two L components are in head-to-head alignment.(ABSTRACT TRUNCATED AT 250 WORDS)
Eukaryotic topoisomerase II is capable of binding two separate nucleic acid helices prior to its DNA cleavage and strand passage events (Zechiedrich, E. L., and Osheroff, N (1990) EMBO J. 9, 4555-4562). Presumably, one of these helices represents the helix that the enzyme cleaves (i.e. cleavage helix), and the other represents the helix that it passes (i.e. passage helix) through the break in the nucleic acid backbone. To determine whether the passage helix is required for reaction steps that precede the enzyme's DNA strand passage event, interactions between Drosophila melanogaster topoisomerase II and a short double-stranded oligonucleotide were assessed. These studies employed a 40-mer that contained a specific recognition/cleavage site for the enzyme. The sigmoidal DNA concentration dependence that was observed for cleavage of the 40-mer indicated that topoisomerase II had to interact with more than a single oligonucleotide in order for cleavage to take place. Despite this requirement, results of enzyme DNA binding experiments indicated no binding cooperativity for the 40-mer. These findings strongly suggest a two-site model for topoisomerase II action in which the passage and the cleavage helices bind to the enzyme independently, but the passage helix must be present for efficient topoisomerase II-mediated DNA cleavage to occur.
We report the cDNA sequence and predicted amino acid sequence of a novel type I keratin, designated as GK50, and show that keratin expression in the goldfish optic nerve is highly complex. The GK50 protein is one of at least three type I keratins expressed in goldfish optic nerve based on both antibody reactivity and blot-binding to the type II keratin ON3. After optic nerve crush in situ hybridization shows a localized increase in GK50 mRNA expression in the crush zone. This is in contrast to ON3 mRNA which shows a localized increase that is limited to the proximal and distal margins of the crush zone, suggesting a diversity of keratin expression in different cell types of the goldfish optic nerve.
We have used platelets as a model system to study the function of c-src in signal transduction and cell adhesion. Numerous proteins were found to be phosphorylated on tyrosine in response to thrombin-induced platelet activation and aggregation. Two phases of phosphorylation were observed, with the second phase, but not the first, being inhibited by blocking platelet aggregation with an Arg-Gly-Asp-Ser tetrapeptide. As a first step towards identifying those proteins phosphorylated on tyrosine and to determine the specific role of p60src during platelet activation, we looked for changes in p60src kinase activity and for associations of p60src with other tyrosine phosphoproteins. The data presented here demonstrate an increase in p60src kinase activity within 1 min of thrombin-induced activation. Furthermore, p60src transiently associates with a tyrosine phosphoprotein during platelet activation and aggregation. This tyrosine phosphoprotein, p80/85, is a previously characterized cytoskeletal substrate for v-src in transformed cells. The data presented here suggest a model in which p60src functions in platelets to link upstream events, such as cell-surface adhesive interactions, with changes in platelet shape and cytoskeletal organization.
As a result of examining regional-specific gene expression in the mouse epididymis, a novel cystatin-related epididymal specific (CRES) gene was identified. Substantial homology between the CRES gene and members of the cystatin family of cysteine proteinase inhibitors was observed at the amino acid level. This homology included the presence of four highly conserved cysteine residues in exact alignment with the cystatins as well as other regions of sequence characteristic of the cystatins. However, unlike the cystatins, the CRES gene does not contain specific highly conserved sequence motifs thought to be necessary for cysteine proteinase inhibitory activity. Also, in contrast to the ubiquitous expression of the cystatin C gene, Northern blot analysis and in situ hybridization demonstrated that the CRES gene is very restricted in its expression. The 0.75-kilobase CRES transcript is dramatically restricted to the very proximal caput region of the epididymis with 15- to 20-fold less expression in the testis and no expression detected in any of the other 24 tissues examined. In addition, the CRES transcript disappears 2-3 weeks after castration, suggesting a dependence on androgens. However, its expression remained undetectable even after the administration of testosterone or dihydrotestosterone. Unilateral castration also resulted in the disappearance of the CRES mRNA from the castrate epididymis, but not from the intact epididymis, suggesting that testicular factors or hormones other than androgens may be involved in the regulation of CRES gene expression. Therefore, the unique sequence of the CRES gene as well as its highly restricted expression and unusual regulation by the testis suggests that it has a very specialized role in the epididymis.
Respiratory syncytial virus (RSV) is the most important cause, throughout the world, of severe viral lower respiratory tract illness in young children. Antibodies are known to mediate resistance to RSV infection and illness. We have isolated a number of human monoclonal Fab fragments to RSV F glycoprotein from a combinatorial antibody library expressed on the surface of phage. One of these neutralized a wide range of virus isolates, 10 subgroup A and 9 subgroup B isolates, with a titer (60% neutralization) of approximately 0.1-1.0 micrograms/ml. Another Fab neutralized diverse isolates at a concentration somewhat higher. These human Fab fragments show great promise for use in the prophylaxis or therapy of serious RSV lower respiratory tract disease. For intramuscular or intravenous administration, whole antibodies will be required, whereas for aerosol application, F(ab')2 or Fab fragments may suffice.