Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0155339 (Brown)
12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Incubation of CMP in 2H2O with 0.5M cysteine methyl ester at p2H 5 and 37 degrees C for 24 h resulted in 43% exchange of 5-H to 5-2H. No deamination of the cytosine nucleus was noted during this treatment. Native and denatured DNA samples from calf thymus were treated in 3H2O with cysteine methyl ester at pH 5 and 37 degrees C for 24 h and incorporation of tritium into each DNA base was determined by enzymic digestion of the treated DNA. The order of the specific radioactivity found was cytosine greater than guanine greater than adenine greater than thymine for denatured DNA and guanine greater than adenine approximately cytosine greater than thymine for native DNA. The ratio of radioactivity for denatured/native was 11.6 for cytosine, 1.5 for guanine, 1.8 for adenine and 1.1 for thymine. Hence the incorporation in cytosine under the reaction conditions is preferential for single-stranded, nonhelical regions of DNA. Escherichia coli glutamic acid tRNA II was treated in 3H2O with 1.24 M cysteine methyl ester at pH 5 and 37 degrees C. The 24-h-treated tRNA was digested with ribonuclease T1 and the fragments were fractionated. Each fragment was then digested with ribonuclease T2 into mononucleotides and the radioactivity distribution among the bases was determined. The average radioactivity found for each of the bases of the four major nucleotides was cytosine greater than guanine approximately adenine greater than uracil. The radioactivity in cytosine varied greatly among the RNase T1 fragments, the ratio of the highest to the lowest radioactivity being 18.7. The corresponding value for guanine was 11.1, for adenine 4.73 and for uracil 3.64. Based on the data obtained, it was deduced that in this tRNA the anticodon loop, the dihydrouridine loop and the extra loop were "exposed" under the conditions employed for the labeling. The 5'-terminal cytosine of the anticodon loop was in a "non-exposed" state, a situation similar to that previously reported for E. coli tyrosine tRNA [Cashmore, A. R., Brown, D. M. & Smith, J. D. (1971) J. Mol. Biol. 59, 359-373] and for E. coli formylmethionine tRNA [Goddard J. P.+Schulman L. H. (1972) J. Biol. Chem. 247, 3864-3867]. Both cytosine 48, located at the 3'-terminal of the extra loop, and guanine 15 in the dihydrouridine loop were in an "emposed" state. This finding does not agree with a tRNA model in which this pair of cytosine and guanine, commonly found in tRNA sequences, forms hydrogen bondings. Positions 30--32, 61--64 and 71, which are located in the stems, were found to be strongly "buried".
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PMID:Conformation of Escherichia coli glutamic acid tRNA II as studied by hydrogen-tritium exchange catalyzed by cysteine methyl ester. 0 69

The cellular and biochemical events which transduce chemical insults into signals for increased expression of the stress-responsive gene gadd 153 were investigated using nephrotoxic cysteine conjugates. In LLC-PK1 cells, cysteine conjugate toxicity is initiated by covalent binding, but depletion of cellular thiols, an increase in cytosolic free calcium, and lipid peroxidation couple the binding to cell death (Chen, Q., Jones, T. W., Brown, P. C., and Stevens, J. L. (1990) J. Biol. Chem. 265, 21603-21611; Chen, Q., Jones, T. W., and Stevens, J. L. (1991) Toxicologist 11, 101, 1991). Three different toxic cysteine conjugates induced gadd 153 mRNA. With S-(1,2-dichlorovinyl)-L-cysteine (DCVC), the induction was both concentration and time-dependent. Preventing the metabolism of DCVC and covalent binding of DCVC-derived reactive metabolites to cellular macromolecules with the beta-lyase inhibitor (aminooxy)acetic acid blocked the induction. However, buffering free calcium with a cell permeable calcium chelator or blocking lipid peroxidation with an antioxidant did not affect the induction of gadd 153 mRNA by DCVC even though these treatments inhibit toxicity. These data suggest that covalent binding of reactive metabolites to cellular macromolecules may serve as a primary signal for the induction of gadd 153 mRNA by nephrotoxic cysteine conjugates. Interestingly, the sulfhydryl agent dithiothreitol, which was nontoxic and prevented the toxicity of DCVC, also induced an increase in gadd 153 mRNA. When both dithiothreitol and DCVC were added to cells, there were no inhibitory or additive effects on expression. Therefore, cellular thiol-disulfide status may also play a role in gadd 153 induction.
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PMID:Activation of the growth arrest and DNA damage-inducible gene gadd 153 by nephrotoxic cysteine conjugates and dithiothreitol. 156 75

All five functional domains of the low density lipoprotein (LDL) receptor were assembled in their modern form more than 350 million years ago, as revealed from the sequence of two cloned cDNAs from the frog Xenopus laevis. The two cDNAs appear to represent duplicated copies of the LDL receptor gene that arose when the entire genome of Xenopus duplicated approximately 30 million years ago. Both frog LDL receptors bound Xenopus LDL with high affinity and human LDL with lower affinity when expressed in monkey COS cells. The receptors also showed high affinity for rabbit beta-migrating very low density lipoprotein and canine apoE-HDLc, both of which contain apolipoprotein E. Each of the seven cysteine-rich repeats in the ligand binding domain of the Xenopus receptors resembles its counterpart in the human, indicating that these repeats had already acquired their independent structures by the time of amphibian development. The cytoplasmic tail of both Xenopus receptors is 86% identical to the human, including the FDNPVY sequence necessary for internalization in coated pits. The attainment of a fully developed receptor structure in Xenopus suggests that earlier forms of the receptor may exist in animals that are older than amphibians. An accompanying paper demonstrates that expression of both Xenopus receptor genes is controlled by a sterol regulatory element that closely resembles the human sequence (Mehta, K.D., Brown, M.S., Bilheimer, D.W., and Goldstein, J.L. (1991) J. Biol. Chem. 266, 10415-10419).
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PMID:The low density lipoprotein receptor in Xenopus laevis. I. Five domains that resemble the human receptor. 170 31

Bacillus thuringiensis produces a 130-140 kDa insecticidal protein in the form of a bipyramidal crystal. The protein in the crystals from the subspecies kurstaki HD-1 and entomocidus was found to contain 16-18 cysteine residues per molecule, present primarily in the disulphide form as cystine. Evidence that all the cysteine residues form symmetrical interchain disulphide linkages in the protein crystal was obtained from the following results: (i) the disulphide diagonal procedure [Brown & Hartley (1966) Biochem. J. 101, 214-228] gave only unpaired cysteic acid peptides in diagonal maps; (ii) the disulphide bridges were shown to be labile in dilute alkali and the crystal protein could be released quantitatively with 1 mM-2-mercaptoethanol; (iii) the thiol groups of the released crystal protein were shown by competitive labelling [Kaplan, Stevenson & Hartley (1971) Biochem. J. 124, 289-299] to have the same chemical properties as exposed groups on the surface of the protein; (iv) the thiol groups in the released crystal protein reacted quantitatively with iodoacetate or iodoacetamide. The finding that all the disulphide linkages in the protein crystal are interchain and symmetrical accounts for its alkali-lability and for the high degree of conservation in the primary structure of the cystine-containing regions of the protein from various subspecies.
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PMID:Characterization of the cysteine residues and disulphide linkages in the protein crystal of Bacillus thuringiensis. 211 Apr 49

We reported previously the purification of a 165-kDa muscle-specific protein identified by virtue of its ability to bind 125I-labeled low density lipoprotein with high affinity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Hoffmann, S. L., Brown, M. S., Lee, E., Pathak, R. K., Anderson, R. G. W., and Goldstein, J. J. (1989) J. Biol. Chem. 264, 8260-8270). The protein is located in the lumen of the sarcoplasmic reticulum, where it has no access to plasma lipoproteins. It binds to 45Ca2+ on nitrocellulose blots and stains metachromatically blue with Stains-all, a cationic dye that stains Ca2+-binding proteins. In the current paper, we have isolated a full-length rabbit cDNA clone for the 165-kDa protein. The deduced amino acid sequence reveals a 852-amino acid protein with the following structural features: 1) an NH2-terminal 27-residue putative signal sequence; 2) a highly repetitive region containing nine nearly identical tandem repeats of 29 residues, each consisting of a histidine-rich sequence HRHRGH, a stretch of 10-11 acidic amino acids, and a sequence containing 2 serines and a threonine in a negatively charged context; 3) a 13-residue stretch of polyglutamic acid; and 4) a COOH-terminal cluster of 14 closely spaced cysteine residues with the repeating pattern of Cys-X-X-Cys suggestive of a heavy metal binding domain. Histidine, aspartic acid, and glutamic acid accounted, respectively, for 13, 12, and 19% of the amino acids. The protein does not share any significant sequence homology with the cell surface low density lipoprotein receptor. Stretches of acidic amino acids are a feature of two other luminal sarcoplasmic reticulum proteins, suggesting that these may be a general feature of luminal sarcoplasmic reticulum proteins. We suggest that the histidine-rich Ca2+-binding protein described in the current study be designated HCP. The role of HCP in Ca2+ homeostasis in the sarcoplasmic reticulum of skeletal and cardiac muscle remains to be determined.
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PMID:Molecular cloning of a histidine-rich Ca2+-binding protein of sarcoplasmic reticulum that contains highly conserved repeated elements. 280 65

Avian liver mitochondrial hydroxymethylglutaryl-CoA synthase contains an active-site cysteine involved in forming the labile acetyl-S-enzyme intermediate. Identification of and assignment of function to this cysteine have been accomplished by use of an experimental strategy that relies upon generation and rapid purification of the S-acetylcysteine-containing active-site peptide under mildly acidic conditions that stabilize the thioester adduct. Automated Edman degradation techniques indicate the peptide's sequence to be Arg-Glu-Ser-Gly-Asn-Thr-Asp-Val-Glu-Gly-Ile-Asp-Thr-Thr-Asn-Ala-Cys-Tyr. The acetylated cysteine corresponds to position 129 in the sequence deduced from cDNA data for the hamster cytosolic enzyme [Gil, G., Goldstein, J.L., Slaughter, C.A., & Brown, M.S. (1986) J. Biol. Chem. 261, 3710-3716]. The acetyl-peptide sequence overlaps that reported for a tryptic peptide that contains a cysteine targeted by the affinity label 3-chloropropionyl-CoA [Miziorko, H. M., & Behnke, C. E. (1985) J. Biol. Chem. 260, 13513-13516]. Thus, availability of these structural data allows unambiguous assignment of the acetylation site on the protein as well as a refinement of the mechanism explaining the previously observed affinity labeling of the enzyme.
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PMID:Identification of the site of acetyl-S-enzyme formation on avian liver mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase. 290 51

The ligand-binding domain of the low density lipoprotein (LDL) receptor is composed of seven cysteine-rich repeats, each approximately 40 amino acids long. Previous studies by van Driel et al. [van Driel, I. R., Goldstein, J. L., Sudhof, T. C. & Brown, M. S. (1987) J. Biol. Chem. 262, 17443-17449] showed that if the first repeat of the ligand-binding domain (encoded by exon 2) is deleted, the receptor fails to bind an anti-LDL receptor monoclonal antibody (IgG-C7) but continues to bind LDL with high affinity. Cultured fibroblasts from a Black South African Xhosa patient (TT) with the clinical syndrome of homozygous familial hypercholesterolemia demonstrated high-affinity cell-surface binding of 125I-labeled LDL but not 125I-labeled IgG-C7. Previous haplotype analysis, using 10 restriction fragment length polymorphic sites, suggested that the patient inherited two identical LDL receptor alleles. The polymerase chain reaction technique was used to selectively amplify exon 2 of the LDL receptor gene from this patient. Sequence analysis of the amplified fragment disclosed a deletion of six base pairs that removes two amino acids, aspartic acid and glycine, from the first cysteine-rich ligand binding repeat. The mutation creates a new PstI restriction site that can be used to detect the deletion. The existence of this mutant allele confirms that the epitope of IgG-C7 is located in the first cysteine-rich repeat and that this repeat is not necessary for LDL binding. The mutant gene produced a normally sized 120-kilodalton LDL receptor precursor protein that matured to the 160-kilodalton form at less than one-fourth the normal rate. Thus, deletion of two amino acids within the first cysteine-rich repeat retards receptor transport from the endoplasmic reticulum to the cell surface, in contrast to deletion of the entire first repeat, which has no effect on receptor maturation.
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PMID:Deletion in the first cysteine-rich repeat of low density lipoprotein receptor impairs its transport but not lipoprotein binding in fibroblasts from a subject with familial hypercholesterolemia. 326 45

We have used mean hydrophobicity and hydrophobic moment calculations to predict the receptor binding domains in apolipoprotein E and in the low density lipoprotein apolipoprotein B-E receptor. In apolipoprotein E, two receptor binding domains, residues 136-160 and 214-236, having a high hydrophilicity and a high mean helical hydrophobic moment, were identified. The first domain has been located experimentally and mutations influencing the hydrophobicity parameters of the binding site have been shown to affect the receptor binding. The second domain is probably, either separately or in combination with the first domain, involved in receptor binding or in heparin binding. In the low density lipoprotein apolipoprotein B-E receptor, six protein domains were identified. In the first domain (residues 1-371), eight hydrophilic maxima, organized in pairs through disulfide bonds, form the four experimentally observed receptor binding sites. These sites consist of repeats of 26 amino acids but differ from those reported by others [Yamamoto, T., Davis, C. G., Brown, M. S., Schneider, W. J., Casey, M. L., Goldstein, J. W. & Russell, D. W. (1984) Cell 39, 27-38]. The second, more hydrophobic, domain (residues 372-640) forms the core of the receptor, explaining its homology with the precursor of mouse epidermal growth factor, while the cysteine residues in the third domain (residues 641-699), interacting with those of the first domain, further stabilize the molecule. Beyond the fourth hydrophilic domain (residues 700-767), to which carbohydrates are linked, a very hydrophobic membrane spanning region (residues 768-789) could be detected easily. The last domain (residues 790-839), situated in the cytoplasma, contains hydrophilic maxima, as this region might interact with clathrin-related proteins. These data suggest that hydrophobicity analysis can detect and predict protein domains: hydrophilic receptor sites as well as hydrophobic core-forming and membrane-spanning regions.
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PMID:Use of hydrophobicity profiles to predict receptor binding domains on apolipoprotein E and the low density lipoprotein apolipoprotein B-E receptor. 345 95

Transpositional mutagenesis of the mer operon of the IncFII plasmid, R100, has revealed a second, trans-acting positive regulatory function. Mutants in this function do not synthesize any of the three small mer operon peptides and have no inducible Hg(II) uptake activity. This second regulatory function is part of complementation group B and so depends upon the activity of the previously described trans-acting positive regulatory function merR. All mutants in this new function map in the amino-terminal 20 kDal of the Hg(II) reductase, suggesting either that this enzyme is also a regulatory protein or that there is a distinct protein whose reading frame is superimposed on that of the Hg(II) reductase. While we have only seen the five previously described mer operon peptides of 69, 66, 15.1, 14 and 12 (13) kDal encoded in minicells by single-copy plasmids, we have observed two new HgCl2-inducible polypeptides of approx. 20 kDal in minicells carrying a multicopy derivative of the mer operon of R100. Sequence data for the Hg(II) reductase region of the related mer operon of the transposon, Tn501 [Brown, N.L., Ford, S.J., Pridmore, R.D. and Fritzinger, D.C., Biochemistry 22 (1983) 4089-4095], shows a second reading frame very rich in cysteine and arginine which overlaps the amino-terminal 20 kDal of the Hg(II) reductase structural gene. We believe that this reading frame is the structural gene for this new regulatory function and propose the name merC (for control).
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PMID:A second positive regulatory function in the mer (mercury resistance) operon. 631 37

The systemic vasculitides are characterized by necrotizing inflammation of blood vessels. Neutrophils are implicated in tissue damage by their presence at the site of injury. They can mediate injury by release of cellular contents including proteinases, cytokines and reactive oxygen species. Antioxidants such as vitamin E and N-acetyl cysteine (NAC) may therefore be predicted to ameliorate oxidative damage in vivo and could be a cheap and non-toxic form of therapy. We examined this hypothesis in an experimental model of vasculitis which has some similarities to human disease, and in which depletion of neutrophils ameliorates tissue injury. Mercuric chloride (HgCl2) treatment induces an autoimmune syndrome and necrotizing leucocytoclastic vasculitis in the Brown Norway (BN) rat; anti-myeloperoxidase (MPO) and anti-glomerular basement (GBM) antibodies are present, and vasculitis is reduced by antimicrobials. Methyl prednisolone given intravenously was effective in reducing tissue injury, demonstrating that the model was responsive to a treatment used in man. Vitamin E and NAC were given as daily injections intraperitoneally to BN rats either before, during or after HgCl2 administration. Serial blood samples were taken for anti-MPO and IgE antibodies, which were assayed by ELISA. Necropsies were performed on animals killed at peak disease. At doses of 50-200 mg/kg per day vitamin E had no beneficial effect on tissue injury, regardless of timing of treatment. NAC at 100 or 200 mg/kg also had no significant protective effect on vasculitis. Autoantibody and IgE levels were not affected by either methyl prednisolone or the antioxidants. The lack of benefit of vitamin E and NAC suggests that oxidative damage, whether generated by neutrophils or other cells, does not play a major role in the pathogenesis of vasculitis, and that antioxidant therapy is unlikely to be of benefit in systemic vasculitis in man.
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PMID:Use of methyl prednisolone and antioxidants in mercuric chloride-induced experimental vasculitis. 792 87


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