Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this report we demonstrate that a transcriptional regulatory element for one gene lies within a second, seemingly unrelated gene. Specifically, the 3' portion of the murine sex-limited protein (slp) gene, located within the class III region of the major histocompatibility complex, contains an element that regulates expression of the linked steroid 21-hydroxylase gene. A 4.2-kilobase (kb) major histocompatibility complex region, located between -2.2 and -6.4 kb upstream of 21OH-A, is required for expression of a chloramphenicol acetyltransferase reporter gene in transgenic mice. Two short regions of DNA, located between -5.3 and -6.0 kb, stimulate chloramphenicol acetyltransferase expression in Y1 adrenocortical tumor cells, and both of these active regions lie within the slp gene. A 21-base pair sequence, which is required for activity of the most 3' region, does not contain any of over 100 previously identified transcriptional regulatory elements. This juxtaposition of structural and regulatory elements of otherwise unrelated genes suggests a mechanism by which the evolutionarily conserved genetic linkage of 21OH-A and slp (or the homologous complement component C4) might provide a selective advantage. Analogous genetic arrangements may explain other examples of conserved linkage of disparate genes.
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PMID:An element regulating adrenal-specific steroid 21-hydroxylase expression is located within the slp gene. 140 May 3

The mechanism of chloramphenicol resistance was examined in a high-level-resistant isolate of Pseudomonas cepacia from a patient with cystic fibrosis. We investigated potential resistance mechanisms, including production of chloramphenicol acetyltransferase, ribosomal resistance, and decreased permeability. This strain (MIC, 200 micrograms/ml) had no detectable chloramphenicol acetyltransferase activity. In in vitro translation experiments in which we compared the resistant isolate with a susceptible strain of P. cepacia, inhibition of amino acid incorporation was equivalent even in organisms that were preincubated with sub-MICs of chloramphenicol. A 21.9-kilobase (kb) fragment of DNA was cloned which coded for chloramphenicol resistance; this fragment was expressed in P. cepacia but not in Escherichia coli. Quantitation of chloramphenicol uptake in the isogenic pair of susceptible and resistant organisms revealed a nearly 10-fold decrease of drug entry into the resistant strain. Comparison of isolated outer membrane proteins and lipopolysaccharide patterns identified no significant differences between the isogenic pair of organisms. We concluded that the mechanism of chloramphenicol resistance in this strain is decreased permeability.
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PMID:Chloramphenicol resistance in Pseudomonas cepacia because of decreased permeability. 271 57

We have previously reported that addition of 8-bromocyclic AMP enhances the stimulatory effect of dexamethasone on the expression of the angiotensinogen gene in mouse hepatoma cells in vitro. Isoproterenol is known to stimulate the synthesis of hepatic intracellular cyclic AMP via beta-adrenergic receptors. To study the possible effect of beta-adrenergic receptors on the expression of the angiotensinogen gene in mouse hepatoma cells, we transiently transfected them with a fusion gene with the 5'-flanking region of the angiotensinogen gene linked to a bacterial chloramphenicol acetyltransferase coding sequence as a reporter, pOCAT (ANG N-1498/+18). The addition of isoproterenol (10(-9) to 10(-5) mol/L) alone had no stimulatory effect on the expression of pOCAT (ANG N-1498/+18). In the presence of dexamethasone (10(-6) mol/L), however, isoproterenol enhanced the stimulatory effect on the dexamethasone on the expression of pOCAT (ANG N-1498/+18). The enhancing effect of isoproterenol was inhibited by the presence of propranolol (beta 1- and beta 2-adrenergic receptor antagonist) and ICI 118,551 (beta 2-adrenergic receptor antagonist) but not by the presence of atenolol (beta 1-adrenergic receptor antagonist). Furthermore, the addition of Rp-cAMP (an inhibitor of protein kinase A I and II) blocked the enhancing effect of isoproterenol. These studies demonstrated that isoproterenol enhances the stimulatory effect of dexamethasone on the expression of the angiotensinogen gene in mouse hepatoma cells via beta 2-adrenergic receptor and cyclic AMP-dependent protein kinase pathways. Our data may be important in understanding the molecular mechanism(s) of the stimulatory effect of catecholamines/glucocorticoid-induced expression of the angiotensinogen gene in the liver.
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PMID:Beta-adrenergic receptors and angiotensinogen gene expression in mouse hepatoma cells in vitro. 784 40

Hexokinases catalyze the phosphorylation of glucose and initiate cellular glucose metabolism. Hexokinase II (HKII) is the principal hexokinase isoform in skeletal muscle, heart, and adipose tissue. Isoproterenol and exogenous cyclic AMP (cAMP) increase HKII gene transcription in L6 myotubes. Various segments of the HKII promoter that direct the expression of the chloramphenicol acetyltransferase reporter gene were transfected into L6 myotubes to identify basal and cAMP response elements. The 5'-flanking region that extends 90 base pairs upstream of the transcription start site includes a CCAAT box and a cAMP response element (CRE); both contribute to basal promoter activity and each provides an independent, maximal response to cAMP. An inverted CCAAT motif, or Y box, located just upstream of the CCAAT box, contributes to basal promoter activity but is not involved in the cAMP response. Homo- and heterodimers composed of the CRE-binding protein and activating transcription factor-1 bind specifically to the CRE. The Y box and the CCAAT box specifically bind the factor NF-Y (also known as CBF).
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PMID:Identification and characterization of basal and cyclic AMP response elements in the promoter of the rat hexokinase II gene. 866 88