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

A set of plasmid expression vectors for cloning of DNA fragments containing open reading frames has been obtained. The plasmids carry the strong leftward promoter of bacteriophage lambda and the translation initiation signals from either the gene ner of bacteriophage Mu or the gene 4 of bacteriophage phi 29. The vectors could overexpress the cloned sequences as fusion peptides at the N terminus with the N-terminal segment of the phi 29 protein p4 or at the C terminus with the Escherichia coli beta-galactosidase from its 8th residue, or both. Alternatively, the cloned sequences could be directed to overproduce proteins in an unfused form. DNA fragments of the hemagglutinin gene from human influenza A virus, have been cloned in one of the plasmid vectors and some potential antigenic determinants have been characterized using monoclonal antibodies.
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PMID:A set of expression plasmids for the synthesis of fused and unfused polypeptides in Escherichia coli. 331 85

A plasmid was constructed that directs expression of the TL-DNA gene 4 protein in E. coli. The different steps of the construction were as follows: i) a region of gene 4 encoding the amino-terminal portion of the protein was fused in frame to DNA encoding an enzymatically active carboxy-terminal fragment of beta-galactosidase. The hybrid gene was poorly expressed from the upstream lambda PL promoter carried by the vector. ii) in order to generate an efficient procaryotic ribosome binding site, a DNA fragment carrying the lambda PR promoter with the nearby Shine-Dalgarno (SD) sequence of gene cro was placed in front of the gene 4-lacZ fusion. A recombinant plasmid, termed pGV793, that expressed efficiently a fused protein 4-beta-galactosidase was identified among the Lac+ clones. DNA sequencing analysis showed that pGV793 carried a hybrid ribosome binding site composed of the cro SD sequence, a five bp sequence and the ATG codon of gene 4. Plasmid pGV793 directed the synthesis of three polypeptides of molecular weight 132 Kd, 126 Kd and 122 Kd that carried beta-galactosidase antigenic determinants. The largest polypeptide had the expected size for the hybrid protein. The fusion proteins which accounted for about 0.5% of the total cellular proteins were purified by immunoadsorption using anti-beta-galactosidase antiserum. iii) the complete gene 4 coding sequence was reconstituted, with the lambda PR promoter in place. The resulting pGV822 plasmid expressed a polypeptide whose molecular weight 27 Kd corresponded to the expected size for the gene 4 product. The pI was about 7.
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PMID:Cloning and expression in Escherichia coli of the TL-DNA gene 4 of Agrobacterium tumefaciens under the control of the PR promoter of bacteriophage lambda. 624 81

Mammalian aging is thought to be partially caused by the diminished capacity of stem/precursor cells to undergo self-renewing divisions. Although many cell-cycle regulators are involved in this process, it is unknown to what extent cell senescence, first identified as irreversible growth arrest in vitro, contributes to the aging process. Here, using a serum-induced mouse oligodendrocyte precursor cell (mOPC) senescence model, we identified esophageal cancer-related gene 4 (Ecrg4) as a senescence inducer with implications for the senescence-like state of postmitotic cells in the aging brain. Although mOPCs could proliferate indefinitely when cultured using the appropriate medium (OPC medium), they became senescent in the presence of serum and maintained their senescent phenotype even when the serum was subsequently replaced by OPC medium. We show that Ecrg4 was up-regulated in the senescent OPCs, its overexpression in OPCs induced senescence by accelerating the proteasome-dependent degradation of cyclins D1 and D3, and that its knockdown by a specific short hairpin RNA prevented these phenotypes. We also show that senescent OPCs secreted Ecrg4 and that recombinant Ecrg4 induced OPC senescence in culture. Moreover, increased Ecrg4 expression was observed in the OPCs and neural precursor cells in the aged mouse brain; this was accompanied by the expression of senescence-associated beta-galactosidase activity, indicating the cells' entrance into senescence. These results suggest that Ecrg4 is a factor linking neural-cell senescence and aging.
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PMID:Esophageal cancer-related gene 4 is a secreted inducer of cell senescence expressed by aged CNS precursor cells. 2040 45