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)

By genetic analysis, we have localized a new mutation, isolated from rho-crp background, responsible for a carbohydrate-positive phenotype. The mutation maps in the rpoB gene coding for the beta-subunit of Escherichia coli RNA polymerase. Using reverse transcriptase analysis of transcripts obtained in vivo and transcription assays in vitro, we have shown that this altered RNA polymerase can efficiently initiate the transcription of the lactose operon in the absence of the cAMP-CRP complex both in vivo and in vitro.
J Mol Biol 1985 Dec 05
PMID:RNA polymerase mutant able to express in vivo and in vitro the lactose operon in the absence of the cAMP-CRP complex. 241 69

In the yeast Kluyveromyces lactis the beta-galactosidase gene is induced by lactose or galactose. As shown here it can also be repressed by glucose but only in some strains. When the LAC9 gene of a repressible strain is substituted by an allele of a non-repressible strain, the beta-galactosidase gene is no longer glucose repressed. LAC9 codes for a regulatory protein homologous to GAL4 which activates transcription in the presence of the inducer. Since the LAC9 product is also present in the repressed strain and binds to DNA in vitro, as shown by DNA footprinting, glucose repression cannot be caused by repression of LAC9 gene expression. Instead, our results demonstrate that glucose repression is mediated by the LAC9 gene product, and is separable from the ability of LAC9 to activate transcription.
Mol Gen Genet 1989 Apr
PMID:Glucose repression of LAC gene expression in yeast is mediated by the transcriptional activator LAC9. 250 50

The structural characteristics and glycosylation properties of the lactogenic receptor were examined in 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS)-solubilized plasma membranes from female mouse liver. The specific binding of the radioiodinated human growth hormone [( 125I]hGH) was displaced with an equivalent potency by both hGH and prolactin. After a mild neuraminidase treatment, this binding was increased by 40%, as a result of an increase in receptor affinity. Affinity chromatography on immobilized lectins revealed that the [125I]hGH-receptor complexes were specifically retained and eluted from ricin lectin-agarose, concanavalin A and lentil lectin, indicating the presence of N-linked glycans. Covalent cross-linking of solubilized [125I]hGH-receptor complexes with disuccinimidyl suberate, followed by analysis by sodium dodecyl sulfate-gel electrophoresis (SDS-PAGE) under reducing conditions, and autoradiography resulted in the appearance of two bands with apparent Mr approximately 62,000 and approximately 100,000. The labelling of these bands was prevented by unlabelled hGH or ovine prolactin (oPrl) but not by bovine growth hormone (bGH). Neuraminidase treatment of the two receptor forms resulted in increased electrophoretic mobility which was inhibited by simultaneous addition of sialyl-lactose, a neuraminidase substrate. The both cross-linked forms were unaffected by endoglycosidase H, while endoglycosidase F decreased the molecular weight of each of the forms by about 8000 Da, yielding bands at Mr approximately 54,000 and approximately 92,000. In conclusion, taking into account that hGH is a Mr 22,000 polypeptide, the two forms of the receptor correspond to glycoproteins of Mr approximately 40,000 and approximately 78,000, respectively. They contain polypeptide backbones of Mr approximately 32,000 and approximately 70,000, and complex N-linked oligosaccharide chains with terminal sialic acid residues which could be involved in receptor binding affinity.
Mol Cell Endocrinol 1989 Aug
PMID:Glycosylation characteristics of the mouse liver lactogenic receptor. 250 88

Low density lipoprotein (LDL) is a spherical particle with a diameter of 22 nm. It consists of an apolipoprotein and a lipid moiety, in which a variety of lipophilic drugs and prodrugs can be incorporated. In the present study, lactose was coupled to the apolipoprotein of LDL by reductive amination (398 +/- 40 residues/LDL particle). After injection into rats, radioactively labeled lactosylated LDL was cleared rapidly from the plasma (half-life, less than 2 min). Ten minutes after injection, the liver contained about 90% of the dose, whereas only small amounts of radioactivity were found in other tissues. Preinjection of N-acetylgalactosamine completely blocked liver uptake, whereas N-acetylglucosamine was ineffective. This indicates that the hepatic recognition site is galactose specific. Subcellular fractionation of liver indicated that the recognition of lactosylated LDL is followed by internalization and degradation of the apolipoprotein in the lysosomes. In the liver, Kupffer cells are mainly responsible for uptake. At 10 min after injection, these cells contained a 70 and 7 times higher amount of lactosylated LDL per mg of cell protein than parenchymal and endothelial cells, respectively. After galactose-specific uptake in parenchymal cells was blocked with asialofetuin, the relative concentration in Kupffer cells was even higher. The hepatic uptake of the lipid moiety of lactosylated LDL, labeled with [3H]cholesteryl oleoyl ether, was identical to that of the 125I-labeled apolipoporotein, which indicates that the particle is taken up as a unit. Thus, lactosylated LDL is taken up rapidly and selectively by Kupffer cells, and it appears that it might be a very effective vehicle for the specific delivery of lipophilic drugs, e.g., immunomodulators, to these cells.
Mol Pharmacol 1989 Sep
PMID:Lactosylated low density lipoprotein: a potential carrier for the site-specific delivery of drugs to Kupffer cells. 255 Jul 81

Neutrophils were found to demonstrate chemotactic responses to pepsinized human placental type IV collagen and its purified aminoterminal 7S domain. The maximal chemotactic responses occur at approximately 400 ng/ml and approximately 30 ng/ml of type IV collagen and 7S collagen, respectively, and are similar in magnitude to the chemotactic response of neutrophils to 10(-8) M FMLP. Human leukemic cells of the HL 60 line display chemotaxis to type IV collagen and 7S collagen only after they are differentiated along the neutrophilic pathway with dimethyl sulfoxide. When detergent extracts of neutrophils are applied to type IV collagen-Affi-Gel resin, a 67 kD protein is retained by the resin and is eluted with guanidine/octyl-beta-glucoside or lactose. This 67 kD polypeptide has an amino acid composition resembling the 67 kD component of the elastin receptor complex, displays immunologic cross-reactivity with antibody to the 67 kD component of the elastin receptor, and binds to elastin and laminin affinity resins. Neutrophil chemotaxis to type IV collagen and 7S collagen is selectively abolished by exposing the test neutrophils to lactose or elastin peptides. We conclude that neutrophils may migrate in vivo to proteolytic fragments of type IV collagen and that this response may be mediated by a lectin-like protein that is similar to the 67 kD component of the elastin receptor.
Am J Respir Cell Mol Biol 1989 Dec
PMID:Neutrophils show chemotaxis to type IV collagen and its 7S domain and contain a 67 kD type IV collagen binding protein with lectin properties. 256 90

A previously unreported endoribonuclease has been identified in Escherichia coli, which has a preference for hydrolysis of pyrimidine-adenosine (Pyd-Ado) bonds in RNA. It was purified about 7000-fold to give a single band after SDS/polyacrylamide gel electrophoresis; the eluted protein gave the same RNase specificity. The sizes of the native and denatured enzymes agreed suggesting that the enzyme exists as a monomer of approximately 26 kDa. It is called RNase M. The only other reported broadly specific endoribonuclease in E. coli is RNase I, a periplasmic enzyme. Based on differences in charge, heat stability and substrate specificity, it was clear that RNase M is not RNase I. The specificity of RNase M was remarkably similar to that of pancreatic RNase A even though the two enzymes differ in charge characteristics and size. Earlier studies had shown that mRNA from the lactose operon of E. coli is hydrolyzed in vivo primarily between Pyd-Ado bonds [Cannistraro et al. (1986) J. Mol. Biol. 192, 257-274] We propose that this major RNase activity accounts for these cleavages observed in vivo and that it is the endonuclease for mRNA degradation in E. coli.
 ...
PMID:Purification and characterization of ribonuclease M and mRNA degradation in Escherichia coli. 265 29

Using standard growth conditions (LB medium, 37 degrees C, induction with 5 mM IPTG) yeast alpha-glucosidase PI expressed under the control of the regulated tac-hybrid promoter results in the synthesis of insoluble aggregated alpha-glucosidase granules in Escherichia coli. Under these conditions active soluble alpha-glucosidase amounts to less than 1% of the heterologously produced protein. However, the amount of soluble active alpha-glucosidase was dramatically increased when the strong tac-hybrid promoter was to a limited extent induced. This was achieved at concentrations of 0.01 mM IPTG or of 1% lactose or lower in a lactose-permease deficient host strain containing the lacIq repressor gene on an R-plasmid. The formation of active soluble alpha-glucosidase was almost 100% when E. coli cells induced in this manner were cultivated under conditions that reduced growth rate, i.e. at decreased temperature, extreme pH values or in minimal and complete media supplemented with different carbon sources.
Mol Gen Genet 1989 Mar
PMID:Control of formation of active soluble or inactive insoluble baker's yeast alpha-glucosidase PI in Escherichia coli by induction and growth conditions. 265 69

We have isolated a new class of mutations in rpoD, the gene encoding the sigma 70 subunit of Escherichia coli RNA polymerase, that alter the transcription initiation properties of RNA polymerase holoenzyme. The rpoD(Lac) mutations increase expression of the lac operon in the absence of CAP-cAMP, allowing a strain lacking adenyl cyclase to grow on lactose. Four of the six alleles isolated have three- to fivefold increases in the amount of lac mRNA and beta-galactosidase per cell. We show that these four mutations increase transcription initiation from the same promoter used by wild-type RNA polymerase. The mutations were mapped and sequenced. One mutation occurs in the codon for amino acid 389 of the sigma 70 polypeptide. The remaining five mutations are clustered, affecting residues 570, 571 and 575. These five mutations are within or near a proposed helix-turn-helix motif in the C terminus of sigma 70.
J Mol Biol 1988 Sep 05
PMID:Mutations in rpoD, the gene encoding the sigma 70 subunit of Escherichia coli RNA polymerase, that increase expression of the lac operon in the absence of CAP-cAMP. 284 53

Plasmids have been constructed with the structural region of the cat gene being under the control of the lactose (lacUV5), tryptophane (trpOP), operons of Escherichia coli, the hybrid trp-lac (tac) promoter and early bacteriophage lambda promoters (PL, PR and PLIT). The expression of chloramphenicolacetyltransferase gene in Escherichia coli cells harbouring such recombinant plasmids and pBR325 as well has been examined by determining the chloramphenicol resistance and studying the enzyme activity of Cm-acetylase. A high level of enzyme synthesis is connected with transcription from PL, PR and tac promoters.
Mol Gen Mikrobiol Virusol 1986 Apr
PMID:[Expression of the chloramphenicol acetyltransferase gene is under control of various promoters of E. coli and phage lambda]. 294 20

We have demonstrated that the replication of the oriC plasmid, carrying the replication origin of the Escherichia coli chromosome, is inhibited by transcriptional readthrough from an oriC flanking region of the plasmid. This was drawn from an examination of the replication of an oriC plasmid, pKZ4, which bears the lacOP segment at the right-hand side of oriC (the asnA side) in such an orientation that transcription from the lac promoter proceeds towards oriC. Replication of pKZ4 was found to be drastically inhibited by inducing transcription from the lac promoter with IPTG, an inducer of the lactose operon. When trp transcription attenuator termination sequences were inserted near the right-hand end of the oriC region of pKZ4, the replication of the plasmid became considerably insensitive to the inhibitory effect of IPTG. This indicates that the inhibition is due to the frequent leftward transcription, which initiates at the lac promoter and proceeds into the oriC region. Since IPTG inhibits the replication of pKZ4, but not that of another coexisting oriC plasmid which is devoid of the lacOP segment, the replication inhibition is judged to act only in cis. Transcription from the promoter of the chloramphenicol resistance gene also caused the inhibition of oriC plasmid replication.
Mol Gen Genet 1985
PMID:Negative control of oriC plasmid replication by transcription of the oriC region. 299 12


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