Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A retrovirus vector was constructed from the genome of avian erythroblastosis virus ES4. The v-erbA sequences of avian erythroblastosis virus were replaced by those coding for neomycin phosphotransferase, creating a gag-neo fusion protein which provides G418 resistance as a selectable marker. The v-erbB sequences following the splice acceptor were replaced by a cloning linker allowing insertion of foreign genes. The vector has been tested in conjunction with several helper viruses for the transmission of G418 resistance, titer, stability, transcription, and the transduction and expression of foreign genes in both chicken embryo fibroblasts and the QT6 quail cell line. The results show that the vector is capable of producing high titers of Neor virus from stably integrated proviruses. These proviruses express a balanced ratio of genome length to spliced transcripts which are efficiently translated into protein. Using the Escherichia coli beta-galactosidase gene cloned into the vector as a test construct, expression of enzyme activity could be detected in 90 to 95% of transfected target cells and in 80 to 85% of subsequently infected cells. In addition, a cDNA encoding the avian erythrocyte band 3 anion exchange protein has been expressed from the vector in both chicken embryo fibroblasts and QT6 cells and appears to function as an active, plasma membrane-based anion transporter. The ectopic expression of band 3 protein provides a visual marker for vector function in these cells.
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PMID:Ectopic expression of the erythrocyte band 3 anion exchange protein, using a new avian retrovirus vector. 217 71

Defective avian leukosis virus (ALV)-based vectors expressing the neo and LacZ genes were constructed under the control of cis-acting elements originated from 4 avian retroviruses: avian erythroblastosis virus (AEV), Rous associated viruses 1 (RAV-1) and 2 (RAV-2), and the Schmidt Ruppin strain of Rous sarcoma virus subgroup D (SR-RSV-D). We used these vectors to study the long-term stability of beta-galactosidase expression (encoded by the LacZ gene) in a permanent cell line from quail fibroblasts (QT6). Infection of the immortalized QT6 cell line with these vectors resulted in unstable beta-galactosidase expression. We determined whether this instability of provirus expression was correlated with: (1) presence of G418 selection; (2) deletion in the proviral genome; (3) hypermethylation of the proviral genome; (4) position of the neo and LacZ genes in the proviral genome; and (5) the transcriptional activity of the long terminal repeat (LTR) elements of proviral vectors. We observed that G418 selection pressure applied to infected QT6 cells lead to a more stable LacZ gene expression. Moreover, our results suggest a correlation between the stability of proviral gene expression and the level of gene expression driven by the LTR elements and depending on the strain origin of these.
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PMID:Influence of expression and cis-acting sequences from avian leukosis viruses (ALVs) on stability of (ALV)-based retrovirus vectors. 767 Oct

We have compared the long-term stability of 2 avian non-replicative retroviral vectors in an infected permanent cell line from quail fibroblasts (QT6). Vectors NL53 and NPL, expressing both the neo and LacZ genes under control of cis-acting elements originated from avian erythroblastosis virus (AEV), are similar to each other except for the presence of the phleomycin-resistance SHble gene fused upstream the reporter LacZ gene, in NPL vector. The use of such vectors, with an uniform backbone, to infect QT6 cells, allowed us to demonstrate that stability of the beta-galactosidase activity encoded by the SHble-LacZ fusion gene remains higher than that encoded by the native LacZ gene, as determined in the same conditions of culture. Moreover, stability of the provirus was dependent on the selection pressure. Here we show that stability of beta-galactosidase activity in infected QT6 cells was obtained with high dose selection for the selectable SHble-LacZ fusion gene.
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PMID:Influence of the nature of the reporter gene and selection pressure on stability of avian retrovirus vectors. 855 47