Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.2.1.7 (BAL)
 1,977 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To investigate the failure of high-level production of hepatitis B viral (HBV) surface antigen (HBsAg), including three authentic forms, large (L), middle (M) and major/small (S) HBsAg, in Escherichia coli, we employed the high-expression vector pGEX containing the glutathione S-transferase-encoding gene (GST) to study HBsAg production. Different fragments of HBV DNA containing the entire pre-S1/pre-S2/S region (for L protein), or partial pre-S1, pre-S2, pre-S1/pre-S2 and pre-S2/S region (for M protein), were fused downstream from the GST gene, in order to obtain five plasmids which encode GST-HBsAg fusion proteins. SDS-PAGE analyses revealed that cells containing plasmids with a full-length S region (pGLS and pGMS) produced undetectable GST-HBsAg fusion proteins, in contrast to those cells harboring plasmids without the S region (pGS1, pGS2 and pGS1S2), which synthesized fusion proteins in 3-10% of the total cellular protein. Using an immunoblot method to screen HBsAg production in cells which harbored plasmids derived from exonuclease BAL 31-digested pGLS, we obtained eight positive clones. Nucleotide sequence analyses of plasmids from the positive clones revealed that termination, deletion or frameshift occurred at the regions encoding either the first or the third transmembrane domain of the major HBsAg. Correlation between the production level of GST-HBsAg fusion proteins and their constituent and arrangement of amino acids (aa) at the last 20 aa among 15 clones suggested that the fusion protein ended with a longer stretch of or a higher ratio of hydrophobic aa had a lower production in E. coli.
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PMID:Deletion or alteration of hydrophobic amino acids at the first and the third transmembrane domains of hepatitis B surface antigen enhances its production in Escherichia coli. 764 92

The lack of apoptosis or programmed cell death in human tumor cells has been suggested to be one factor allowing uncontrolled growth of neoplasms. We have developed a mouse monoclonal antibody (MAb) that induces programmed cell death in a human acute leukemia cell line (KM-3) of the pre B-cell type. Stable, antibody-producing hybridomas were produced by fusing mouse myeloma cells to spleen cells from mice immunized with viable KM-3 cells. Incubation of KM-3 cells with the MAb (designated anti-BAL) resulted in growth inhibition and subsequent cell death within 2-3 days. Anti-BAL required cross-linking with a rabbit anti-mouse antibody to induce DNA fragmentation typical of apoptosis. Immunoblotting experiments with anti-BAL identified a 37-kDa protein, apparently different from any previously described apoptosis-related surface antigen. Strongest expression of the antigen was generally found on cells of lymphoid or myeloid origin. However, several other cell types such as fibroblasts and endothelial cells were also stained by anti-BAL in flow cytometry but less intensively. Despite the apparent presence of this cell surface-bound 37-kDa antigen on several normal and malignant cell types, anti-BAL induced cell death only in human malignant cell lines expressing a more immature phenotype.
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PMID:A cell surface antigen (BAL) defined by a mouse monoclonal antibody inducing apoptosis in a human lymphocytic leukemia cell line. 818 58