Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have developed conditions for efficient cDNA cloning of nanogram amounts of purified mRNAs coding for cystathionine beta-synthase [L-serine hydro-lyase (adding homocysteine), EC 4.2.1.22] and for the cytosolic precursors of mitochondrial ornithine transcarbamylase (carbamoylphosphate:L-ornithine carbamoyltransferase, EC 2.1.3.3) and the beta subunit of propionyl-CoA carboxylase [propanoyl-CoA: carbon-dioxide ligase (ADP-forming), EC 6.4.1.3]. The three mRNAs, prepared by sequential immunoselection from the same batch of rat liver polysomes, were pooled (20 ng each), and cDNA was synthesized by using avian reverse transcriptase. The second DNA strand was prepared by "nick-translation repair" of the cDNA . mRNA hybrid with RNase H, polymerase I, and DNA ligase from Escherichia coli. The double-stranded (ds) DNA was tailed with deoxycytidine residues, annealed with Pst I-cut/dG-tailed pBR322, and used to transform E. coli. The library generated by this three-step procedure contained 5000 independent colonies. A 550-base-pair (bp) cDNA clone of the beta subunit of propionyl-CoA carboxylase was detected by hybrid-selected translation; it was then used to screen the library for longer cDNAs. Two hybridizing cDNAs, 1200 and 1000 bp long with a 200-bp overlap, representing together a full-length copy of the coding region and 446 bp of 3' untranslated sequence, were recovered. Each plasmid mapped to the region q13.3----q22 of human chromosome 3. Cystathionine beta-synthase clones were obtained by screening the library with a single-stranded [32P]cDNA prepared directly from the highly purified synthase mRNA by reverse transcriptase. The longest hybridizing cDNA of 1700 bp was used in hybrid-selected translation and detected a polypeptide of 63 kDa, identical in size to rat liver synthase. In situ hybridization of this cDNA to q22 of human chromosome 21 confirmed two previous tentative assignments of the synthase locus to this chromosome.
 ...
PMID:Cloning and screening with nanogram amounts of immunopurified mRNAs: cDNA cloning and chromosomal mapping of cystathionine beta-synthase and the beta subunit of propionyl-CoA carboxylase. 345 73

The cystathionine beta-synthase (CBS) gene encodes an enzyme that catalyzes the synthesis of cystathionine in the trans-sulfuration pathway and is subject to tight regulation because of its critical role in antioxidant and methylation metabolism. The expression level of CBS in 120 hepatocellular carcinoma (HCC) specimens evaluated by real-time reverse transcriptase PCR (RT-PCR) is markedly lower than in surrounding non-cancerous liver (P<0.0001). The correlation between CBS gene expression in HCC and clinicopathological parameters or survival of HCC patients was statistically analyzed in the present study. Our study demonstrated that reduced CBS expression is significantly correlated with high tumor stage (P=0.0019), high Edmondson grade (P=0.00084), and high AFP level (P=6.2x10(-5)). Interestingly, a survival analysis showed that a significantly shorter overall survival (OS) time is observed in patients with reduced CBS expression (P=0.0022), although CBS expression was determined not to be an independent prognostic factor for OS (P=0.071) after considering tumor stage, tumor size, and AFP level. However, for the 62 patients with low AFP levels (<100 ng/ml), reduced CBS expression was found to be an independent prognostic factor for OS (P=0.0042) after considering tumor stage and tumor size. Thus, the expression level of CBS mRNA could be useful to predict clinical outcome of HCC, especially for patients with low AFP levels.
 ...
PMID:Expression of cystathionine beta-synthase is downregulated in hepatocellular carcinoma and associated with poor prognosis. 1942 22

To identify copper homeostasis genes in Rhodobacter capsulatus, we performed random transposon Tn5 mutagenesis. Screening of more than 10,000 Tn5 mutants identified tellurite resistance gene trgB as a so far unrecognized major copper tolerance determinant. The trgB gene is flanked by tellurite resistance gene trgA and cysteine synthase gene cysK2. While growth of trgA mutants was only moderately restricted by tellurite, trgB and cysK2 mutants were severely affected by tellurite, which implies that viability under tellurite stress requires increased cysteine levels. Mutational analyses revealed that trgB was the only gene in this chromosomal region conferring cross-tolerance towards copper. Expression of the monocistronic trgB gene required promoter elements overlapping the trgA coding region as shown by nested deletions. Neither copper nor tellurite affected trgB transcription as demonstrated by reverse transcriptase PCR and trgB-lacZ fusions. Addition of tellurite or copper gave rise to increased cellular tellurium and copper concentrations, respectively, as determined by inductively coupled plasma-optical emission spectroscopy. By contrast, cellular iron concentrations remained fairly constant irrespective of tellurite or copper addition. This is the first study demonstrating a direct link between copper and tellurite response in bacteria.
 ...
PMID:Tellurite resistance gene trgB confers copper tolerance to Rhodobacter capsulatus. 2276 5