Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We sought to isolate and partially purify proteins corresponding to the binding element of the imidazoline receptor (IR) from adrenal chromaffin cell membranes. These cells express IRs of the I-2 subclass and not alpha 2-adrenergic receptors. Proteins were solubilized in 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate-containing buffer and were assayed by binding of [3H]idazoxan, an imidazoline radioligand. Two ligand affinity resins, p-aminoclonidine-Trisacryl GF-2000 (PAC-ReactiGel) and idazoxan-PharmaLink agarose (IDA-agarose), were synthesized. These allowed purification by single-step affinity chromatography of a major receptor binding protein component of 70 kDa, as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and [3H]idazoxan binding assay. The purified imidazoline-binding proteins from IDA-agarose and PAC-ReactiGel had similar affinities for the radioligand [3H]idazoxan (Kd = 3.7 and 4.9 nM, respectively) and a displacement profile, showing sensitivity to imidazoline agents (cirazoline > clonidine) and insensitivity to catecholamines and adrenergic agents (epinephrine approximately rauwolscine), that was similar to that of the intact membrane receptor. The imidazoline-binding protein did not bind to concanavalin A, suggesting that it may not be glycosylated or that the sugar moieties present are not recognized by this lectin. The results indicate that IR and alpha 2 receptor proteins may be biochemically distinct and that IDA-agarose and PAC-ReactiGel columns are useful for purification of sufficient quantities of imidazoline-binding proteins to allow for structural and functional studies of the IR.
Mol Pharmacol 1992 Nov
PMID:Isolation and characterization of imidazoline receptor protein from bovine adrenal chromaffin cells. 143 52

Two isoenzymic forms of aspartate aminotransferase are present in the plant fraction of developing lupin root nodules. One of these forms, aspartate aminotransferase-P2 (AAT-P2), increases dramatically with the onset of biological nitrogen fixation and is associated with the assimilation of ammonia by the plant in the Rhizobium-legume symbiosis. A day 18 lupin nodule cDNA library in the lambda ZapII vector was immunoscreened with a monoclonal antibody specific for AAT-P2 and yielded two near-full-length 1700 bp clones. These clones were sequenced. Amino acid sequences from three peptides derived from immunopurified AAT-P2 were aligned, and showed 100% homology with the amino acid sequence deduced from the cDNA clones. The DNA sequence showed 50% homology with AAT sequences from a range of animal sources. Conversion of the clones to the phagemid form allowed their expression in Escherichia coli where both exhibited enzyme activity that could be immunoprecipitated with AAT-P2-specific monoclonal antibodies. Western blot analysis revealed protein moieties with molecular masses of 39, 43, 45 and 55 kDa. The 5' end of the clones coded for a hydrophobic leader sequence of about 50 amino acids indicative of a targeting sequence and consistent with the plastid localisation of nodule AAT-P2.
Plant Mol Biol 1992 Jun
PMID:Molecular cloning of a cDNA encoding aspartate aminotransferase-P2 from lupin root nodules. 162 92

We have isolated an alfalfa leaf cDNA clone that encodes aspartate aminotransferase (AAT, EC 2.6.1.1) by direct complementation of an Escherichia coli aspartate auxotroph with a plasmid cDNA library. DNA sequence analysis of the recombinant plasmid, pMU1, revealed that a 1514 bp cDNA was inserted in the correct orientation and in-frame with the start of the lacZ coding sequence in the vector, pUC18. The resulting fusion protein is predicted to be 424 amino acids in length with a molecular weight of 46387 Daltons. The cDNA-encoded protein has a characteristic pyridoxal phosphate attachment site motif and has substantial amino acid sequence homology to both animal and bacterial AATs. Plasmid pMU1 encodes an AAT with a Km for aspartate of 3.3 mM, a Km for 2-oxoglutarate of 0.28 mM, and a pH optimum between 8.0 and 8.5. Several lines of evidence including Western blot analysis, the isoelectric point of the encoded protein, and the effect of pH on the activity of the fusion protein, suggest that the cDNA encodes the isozyme AAT-1 rather than AAT-2. Northern blot analysis showed that the aat-1 clone hybridized to a 1.6 kb transcript present in alfalfa leaves, roots and nodules. The relative concentrations of aat-1 mRNA in these tissues were 1:2:5, respectively. Thus, transcription of aat-1 appears to be induced during nodule development. Southern blot analysis suggested that AAT-1 in alfalfa is encoded by either a single-copy gene or a small, multigene family.
Mol Gen Genet 1991 Dec
PMID:Isolation and analysis of a cDNA clone that encodes an alfalfa (Medicago sativa) aspartate aminotransferase. 175 49

An investigation of the crystal structure of cytosolic pig-heart aspartate aminotransferase (AAT, E.C.2.6.1.1) was carried out to determine the structural requirements for ligand recognition by the active site. Structural differences were observed between the two active sites of the AAT dimer. The natural ligand, L-aspartate, was docked into both active sites using various methods. However, due to structural differences, the ligand was able to form all the necessary interactions for initial binding in only one of the active sites. The program GRID (P.J. Goodford, J. Med. Chem. 1985, 28, 849-857) was used to predict favorable binding sites for the functional groups of the aspartate ligand. These binding sites corresponded to the position of the docked aspartate ligand, indicating that substrate recognition takes place before any major conformational changes occur within the enzyme.
J Mol Graph 1990 Jun
PMID:Aspartate aminotransferase: investigation of the active sites. 228 53

An in vitro model system is described for studying the problem of loss of steroid sensitivity in breast cancer cells. Growth of cloned oestrogen-sensitive human breast cancer cells in the long-term absence of steroid gives rise to a population of oestrogen-insensitive cells. In ZR-75-1 cells, the effect is clonal but occurs at high frequency suggesting a mechanism affecting a wide proportion of the cell population synchronously. This does not involve any reduction in oestrogen receptor number. Furthermore, there is no coordinated loss of oestrogen-sensitive molecular markers, showing that oestrogen receptors remain not only present but functional. These growth changes are not accompanied by any loss of growth inhibition by antioestrogen. Although steroid deprivation does not result in loss of oestrogen-sensitive markers, this does not hold true for other steroids. There was a reduction in progestin, androgen and glucocorticoid regulation on transfected LTRs. Loss of steroid-sensitive growth was accompanied by changes in response to exogenous growth factors and altered endogenous growth factor mRNA production. Steroid-deprived T-47-D cells acquire sensitivity to stimulation by TGF beta and have raised TGF beta 1 and TGF beta 2 mRNA levels. ZR-75-1 cells are growth inhibited by TGF beta and have reduced TGF beta 1 mRNA levels. In MCF-7 cells, increased IGFII mRNA, following transfection, can result in an increased basal cell growth rate in the absence of steroid. These findings are discussed in relation to possible autocrine mechanisms in the loss of steroid sensitivity of breast cancer cells.
J Steroid Biochem Mol Biol 1990 Dec 20
PMID:Transition of human breast cancer cells from an oestrogen responsive to unresponsive state. 228 87

Androgens induce the synthesis of murine beta-glucuronidase (GUS) 10-fold in the submaxillary gland of B6.PAC-Gusn mice without a concomitant increase in GUS mRNA levels. Since the rate of GUS synthesis per mRNA molecule, or translational yield, is a function of both the efficiency with which the message is translated and the fraction of newly made polypeptides that are incorporated into GUS tetramers, we conclude that androgen induces at least one of these components in the submaxillary gland of B6.N mice. Genetic variation in the submaxillary gland induction response was tested for using six congenic mice strains, each carrying a different haplotype of the Gus gene complex on a C57BL/6J genetic background. The results indicate that the DNA sequences determining androgen responsiveness of the Gus gene in the submaxillary gland are linked to the Gus gene complex and that the DNA sequences determining the submaxillary gland response are distinct from those determining the androgen induction of GUS mRNA in kidney.
Mol Endocrinol 1988 Aug
PMID:Androgen induction of beta-glucuronidase translational yield in submaxillary gland of B6.N mice. 246 79

We have previously identified a unique site, pac, from which packaging of precursor concatameric viral DNA into proheads starts during the maturation process of bacteriophage CP-T1. The direction of this packaging was determined from restriction enzyme cleavage patterns of CP-T1 DNA. A restriction enzyme generated fragment containing pac was cloned and the surrounding DNA region sequenced. Analysis of the nucleotide sequence revealed numerous repeat regions related to the consensus sequence PuagttGAT.AAT.aa.t. Within the sequenced region an open reading frame encoding a 12260 Mr protein was also identified. This protein appears to share homology with the binding domains of known DNA binding proteins and may represent a putative Pac terminase possessing the specific endonuclease activity required for cleavage at the pac site. Minicell analysis of deletion derivatives of the pac-containing clone revealed a protein of approximately 12,900 Mr encoded within this same region, confirming that this Pac protein is phage encoded.
Mol Gen Genet 1988 Jun
PMID:Molecular analysis of the packaging signal in bacteriophage CP-T1 of Vibrio cholerae. 341 20

It is shown, that DNA hydrolysis catalyzed by E. coli DNA polymerase I is inhibited, when a reaction mixture contains one type of deoxynucleoside 5'-triphosphate (dNTP). When the reaction mixture contains [32P]dNTP, then [32P] is incorporated into DNA and v. v. (32P) from DNA is transferred into dNTP. The nucleotide exchange between DNA and dNTP in the assay mixture is observed only in the case, when the chemical nature of nucleotide residue of dNTP and that of the 3'-terminus of DNA is the same. Analysis of products of DNA hydrolysis in the presence of one type of dNTP using electrophoresis in polyacrylamide gel shows that most of the DNA molecules are terminated at the 3'-termini by the dNMP residue of the same chemical nature as the dNTP in the assay mixture. However, in some cases DNA molecules contain one additional nucleotide residue. This phenomenon can be explained by incorporation of one additional dNMP residue originating from dNTP only in those cases, when a non-typical base pairing of this nucleotide residue with a template residue readily takes place. The above-mentioned facts can be interpreted within the model for DNA hydrolysis with involvement of two intermediate covalent forms of dNMP residues with DNA polymerase I; one dNMP-intermediate should be placed at the elongation center and the other--at the hydrolysis center. The DNA hydrolysis by 3'----5' exonuclease activity of DNA polymerase I proceeds through these two covalent forms. DNA polymerases alpha from calf thymus and T4 phage do not catalyze the nucleotide exchange between DNA and dNTP from the reaction media.
Mol Biol (Mosk)
PMID:[Non-canonical nucleotide exchange catalyzed by Escherichia coli DNA-polymerase I and the two-center model of the mechanism of action of this enzyme]. 353 50

The amidase genes of Pseudomonas aeruginosa were inserted into a lambda replacement vector following cleavage with the restriction endonuclease HindIII. The recombinant lambdaami was detected by enhanced growth of Escherichia coli around plaques of the recombinant phage on minimal medium containing acetamide as the nitrogen source. Low levels of amidase activity were detected in E. coli cultures infected with lambdaami and these were sufficient to allow growth with acetamide as nitrogen source. Lysis-defective derivatives of lambdaami were made by introducing Q-, S-, mutations. Cultures of E. coli infected with lambdaamiQ-S- synthesised amidase as the major protein. The amidase produced by these cultures was identical to that produced by PAC strains of P. aeruginosa in substrate specificty, thermal stability and immunological cross-reaction.
Mol Gen Genet 1980 Jan
PMID:The construction in vitro of derivatives of bacteriophage lambda carrying the amidase genes of Pseudomonas aeruginosa. 624 42

We have determined the nucleotide sequence at the distal end of the heat-labile enterotoxin subunit A (LT-A) gene (toxA) originating from human enterotoxigenic Escherichia coli. The sequenced region covers the entire LT-A2 region and a part of the LT-A1 region. In confirming our previous prediction based on product analysis of clones toxA regions, the data suggest the overlapping of the distal end (5'-TTA TGA) of toxA with the proximal end (5'-ATG AAT) of the LT subunit B gene (toxB), in the sequences 5'-TTATGAAT. Some additional characteristics of the LT operon as well as of the products are discussed.
Mol Gen Genet 1982
PMID:Overlapping genes in the heat-labile enterotoxin operon originating from Escherichia coli human strain. 675 77


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