scholarly journals Partial purification, characterization and translation in vitro of rat liver metallothionein messenger ribonucleic acid

1978 ◽  
Vol 175 (3) ◽  
pp. 841-852 ◽  
Author(s):  
R D Andersen ◽  
U Weser
Keyword(s):  
Rat Liver ◽  
Wheat Germ ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Specific Radioactivity ◽  
Sedimentation Coefficient ◽  
Free System ◽  
High Specific Radioactivity ◽  
Cdcl2 Treatment

Poly(A)+ (polyadenylated) mRNA coding for metallothioneins was purified 13-fold from rat liver polyribosomes and was identified by its ability to direct the biosynthesis of these proteins in a wheat-germ cell-free system. The carboxymethylated products of the protein-synthesizing system in vitro were analysed with sodium dodecyl sulphate/20% polyacrylamide-gel electrophoresis. The labelled compounds [3H]serine and [35S]cysteine were incorporated at high specific radioactivity into proteins that co-migrated with authentic metallothioneins. No [3H]leucine incorporation was found, in agreement with the amino acid composition of the metallothioneins. Metallothionein mRNA had a sedimentation coefficient of 9 S and carried a maximum of four ribosomes. At 5 h after a subcutaneous injection of ZnCl2 or CdCl2 (10 mumol/kg body wt.), the amount of this mRNA increased approx. 2- and 4-fold respectively, on the basis of translation in vitro. The increase in metallothionein mRNA (defined by translation in the wheat-germ system) was transient and, after CdCl2 treatment, fell back to control values by 17 h. Metallothioneins constituted a maximum of 0.8% of the total protein products synthesized in the wheat-germ system by total mRNA isolated from rat liver after CdCl2 treatment.

scholarly journals Trichomonas vaginalis Lipophosphoglycan Mutants Have Reduced Adherence and Cytotoxicity to Human Ectocervical Cells

2005 ◽  
Vol 4 (11) ◽  
pp. 1951-1958 ◽  
Author(s):  
Felix D. Bastida-Corcuera ◽  
Cheryl Y. Okumura ◽  
Angie Colocoussi ◽  
Patricia J. Johnson
Keyword(s):  
Wheat Germ Agglutinin ◽  
Parent Strain ◽  
Trichomonas Vaginalis ◽  
Wheat Germ ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Host Cells ◽  
Chemical Mutagenesis ◽  
Reduced Adherence

ABSTRACT The extracellular human pathogen Trichomonas vaginalis is covered by a dense glycocalyx thought to play a role in host-parasite interactions. The main component of the glycocalyx is lipophosphoglycan (LPG), a polysaccharide anchored in the plasma membrane by inositol phosphoceramide. To study the role of LPG in trichomonads, we produced T. vaginalis LPG mutants by chemical mutagenesis and lectin selection and characterized them using morphological, biochemical, and functional assays. Two independently selected LPG mutants, with growth rates comparable to that of the wild-type (parent) strain, lost the ability to bind the lectins Ricinnus comunis agglutinin I (RCA120) and wheat germ agglutinin, indicating alterations in surface galactose and glucosamine residues. LPG isolated from mutants migrated faster than parent strain LPG on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting the mutants had shorter LPG molecules. Dionex high-performance anion exchange chromatography with pulsed amperometric detection analyses revealed galactosamine, glucosamine, galactose, glucose, mannose/xylose, and rhamnose as the main monosaccharides of T. vaginalis parent strain LPG. LPG from both mutants showed a reduction of galactose and glucosamine, corresponding with the reduced size of their LPG molecules and inability to bind the lectins RCA120 and wheat germ agglutinin. Mutant parasites were defective in attachment to plastic, a characteristic associated with avirulent strains of T. vaginalis. Moreover, the mutants were less adherent and less cytotoxic to human vaginal ectocervical cells in vitro than the parental strain. Finally, while parent strain LPG could inhibit the attachment of parent strain parasites to vaginal cells, LPG from either mutant could not inhibit attachment. These combined results demonstrate that T. vaginalis adherence to host cells is LPG mediated and that an altered LPG leads to reduced adherence and cytotoxicity of this parasite.

The kinetics of in vitro reoxidation and reduction of the inter heavy–light chain disulfide bond in an unusual murine immunoglobulin G myeloma protein lacking inter-heavy chain disulfide bonds

1979 ◽  
Vol 57 (3) ◽  
pp. 279-285 ◽  
Author(s):  
Maire E. Percy ◽  
Lebe Chang ◽  
Catherine Demoliou ◽  
Reuben Baumal
Keyword(s):  
Disulfide Bond ◽  
Disulfide Bonds ◽  
Peptide Mapping ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Sedimentation Coefficient ◽  
Disulfide Bridge ◽  
Myeloma Protein ◽  
Kinetics Of

After 5 years of subcutaneous transfer in Balb/C mice, our MOPC 173 myeloma tumour line (originally an IgG2a,κ H2L2-producer) exclusively synthesized an unusual IgG2b,κ protein lacking inter-heavy (H) chain disulfide bonds. This protein was designated MOPC 173B. On sodium dodecyl sulfate – polyacrylamide gel electrophoresis, it migrated with an apparent molecular weight of 77 000; following complete reduction and alkylation, the mobilities of its constituent H and light (L) chains were found to differ slightly from those of MOPC 173 H2L2. MOPC 173B was serologically identical to another typical IgG2b,κ myeloma protein, MOPC 195, and peptide mapping studies showed that it possessed only the inter H–L disulfide bond characteristic of typical IgG2b,κ proteins. In a nondissociating solvent, the sedimentation coefficient of the protein was 6.3S even at concentrations as low as 0.2 mg/ml, indicating that noncovalent interactions existed between two half-molecule subunits. Since this unusual IgG myeloma protein contained only a single category of interchain disulfide bridge, the inter H–L bond, it was an ideal model system for characterization of the kinetics of formation and reduction of interchain disulfide bonds. The kinetics of the glutathione-catalyzed reoxidation of the inter H–L disulfide bridge in MOPC 173B followed an apparent second-order rate equation. In contrast, reduction of its inter H–L bridge under anaerobic conditions with dithioerythritol in excess, was strictly a first-order process and not a simple reversal of the reoxidation. These studies provide the basis for the more complex mathematical models that describe the reoxidation and reduction of typical immunoglobulin molecules.

scholarly journals Role of membrane-bound and free polyribosomes in the synthesis of cytochrome c in rat liver

1974 ◽  
Vol 140 (2) ◽  
pp. 157-167 ◽  
Author(s):  
Néstor F. González-Cadavid ◽  
Carmen Sáez De Córdova
Keyword(s):  
Endoplasmic Reticulum ◽  
Cytochrome C ◽  
Rat Liver ◽  
Cell Structure ◽  
Polyacrylamide Gel Electrophoresis ◽  
Mitochondrial Protein ◽  
Sodium Dodecyl ◽  
Membrane Bound

The functional distinction of membrane-bound and free polyribosomes for the synthesis of exportable and non-exportable proteins respectively is not so strict as was initially thought, and it was therefore decided to investigate their relative contribution to the elaboration of an internal protein integrated into a cell structure. Cytochrome c was chosen as an example of a soluble mitochondrial protein, and the incorporation of [14C]leucine and δ-amino[14C]laevulinate into the molecule was studied by using different ribosomal preparations from regenerating rat liver. A new procedure was devised for the purification of cytochrome c, based on ion-exchange chromatography combined with sodium dodecyl sulphate–polyacrylamide-gel electrophoresis. In spite of cytochrome c being a non-exportable protein, the membrane-bound polyribosomes were at least as active as the free ribosomes in the synthesis in vitro of the apoprotein and the haem moiety. The detergent-treated ribosomes could also effect the synthesis of cytochrome c, although at a lower rate. Since in liver more than two-thirds of the ribosomes are bound to the endoplasmic-reticulum membranes, it is considered that in vivo they are responsible for the synthesis of most of the cytochrome c content of the cell. This suggests that in secretory tissues the endoplasmic reticulum plays a predominant role in mitochondrial biogenesis, although free ribosomes may participate in the partial turnover of some parts of the organelle. The hypothesis on the functional specialization of the different kinds of ribosomes was therefore modified to account for their parallel intervention in the synthesis of proteins associated with membranous structures.

scholarly journals Gene expression in Acetabularia. I. Calibration of wheat germ cell-free translation system proteins as internal references for two-dimensional electrophoresis

1982 ◽  
Vol 58 (1) ◽  
pp. 23-33
Author(s):  
R.L. Shoeman ◽  
H.G. Schweiger
Keyword(s):  
Germ Cell ◽  
Isoelectric Point ◽  
Wheat Germ ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
In Vitro Translation ◽  
Translation System ◽  
Two Dimensional ◽  
Free Translation

Modification of existing two-dimensional techniques enables isoelectric focusing and sodium dodecyl sulphate polyacrylamide gel electrophoresis of complex mixtures of proteins to be completed within 8 h. The method was optimized to separate the protein components of a wheat germ cell-free translation system, providing a statistically proven resolution better than 0. 03 of a pH unit for the isoelectric point and 1000 for Mr. Fourteen of the more than 300 proteins separated were characterized with respect to Mr and isoelectric point relative to standard proteins under the same conditions. Stained wheat germ proteins thus serve as internal standards for analysis of in vitro translation products.

Cell-free synthesis of α and β subunits of human chorionic gonadotrophin with polyribosomes from early placenta

1980 ◽  
Vol 95 (1) ◽  
pp. 90-96 ◽  
Author(s):  
Takeshi Maruo ◽  
S. S. Koide
Keyword(s):  
Wheat Germ ◽  
Sodium Dodecyl ◽  
Placental Tissue ◽  
First Trimester ◽  
Synthetic Activity ◽  
Α Subunit ◽  
Free System ◽  
Β Protein ◽  
Α And Β Subunits

Abstract. Polyribosomes were prepared from first trimester human placenta and assayed for protein synthetic activity in the cell-free translatory system derived from wheat germ or from first trimester placental tissue. High incorporation of [3H]proline was observed, whereas incorporation of [3H]glucosamine did not occur. The radiolabelled proteins synthesized by the wheat germ cell-free system were immunoprecipitated with specific antisera for hCG, α- and β-subunit and analyzed by electrophoresis on sodium dodecyl sulphate-polyacrylamide gels. The apparent molecular weight of the immunoprecipitable CG-α-protein was estimated to be 15 000 daltons, while that of the immunoprecipitable β-protein was about 24 000 daltons. Since the molecular weights of the polypeptide part of authentic α and β subunits are 10 200 and 16 000 daltons, respectively, the cell-free products may represent their precursor protein forms; pre-CG-α and pre-CG-β. The rates of production of hCG, α and β proteins by in vitro incubation of placental polyribosomes with the wheat germ translating system were determined by the respective homologous radioimmunoassays. It is noteworthy that CG-β-protein production was highest during the initial 15 min of incubation and became limited subsequently, whereas an increase in hCG and α-protein formation was observed at 90 min of incubation. The present results suggest that the placental polyribosomes contain mRNA for α- and β-subunits. Earlier accelerated synthesis of CG-β protein might be required for the subsequent association with the newly synthesized α-subunit protein to form hCG.

scholarly journals Role of Surface Proteins in Vibrio cholerae Attachment to Chitin

1999 ◽  
Vol 65 (3) ◽  
pp. 1348-1351 ◽  
Author(s):  
Renato Tarsi ◽  
Carla Pruzzo
Keyword(s):  
Vibrio Cholerae ◽  
Gel Electrophoresis ◽  
Wheat Germ ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Surface Proteins ◽  
Molecular Sizes ◽  
Pronase E

ABSTRACT The role of surface proteins in Vibrio choleraeattachment to chitin particles in vitro was studied. Treatment ofV. cholerae O1 ATCC 14034 and ATCC 14035 with pronase E reduced the attachment of bacteria to chitin particles by 57 to 77%. A statistically significant reduction was also observed when the attachment to chitin was evaluated in the presence of homologous Sarkosyl-insoluble membrane proteins (MPs) (67 to 84%),N-acetylglucosamine (GlcNAc) (62%), the sugar that makes up chitin, and wheat germ agglutinin (40 to 56%), a lectin that binds GlcNAc. The soluble oligomersN,N′-diacetylchitobiose orN,N′,N"-triacetylchitotriose caused an inhibition of 14 to 23%. Sarkosyl-insoluble MPs able to bind chitin particles were isolated and visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; two of these peptides (molecular sizes, 36 and 53 kDa) specifically bind GlcNAc.

Site of synthesis of metallothionein in rat liver

1981 ◽  
Vol 59 (4) ◽  
pp. 301-306 ◽  
Author(s):  
M. George Cherian ◽  
Sharon Yu ◽  
Colvin M. Redman
Keyword(s):  
Rat Liver ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Adult Rat ◽  
Cadmium Treatment ◽  
Reticulocyte Lysate

Free and membrane-attached polysomes were isolated from the livers of normal and cadmium-treated rats, and were translated using L-[35S]cysteine and a nuclease-treated reticulocyte lysate system. The translation products were analyzed for radioactive metallothionein by immunoprecipitation with antibodies to rat cadmium metallothionein followed by sodium dodecyl sulfate – polyacrylamide gel electrophoresis. In both normal and cadmium-treated rats, radioactive metallothionein was produced by free polysomes but not by membrane-attached polysomes. Cadmium treatment did not increase the in vitro ability of polysomes to synthesize metallothionein. As a control, the translation products of these two classes of polysomes were also analyzed for radioactive albumin and it was confirmed that membrane-attached polysomes produce albumin but do not synthesize metallothionein. The cell-free synthesis of metallothionein by free polysomes was also demonstrated by isolation of nascent metallothionein by Sephadex gel filtration and DEAE-cellulose chromatography. In adult rat liver there are two forms of metallothionein and both were produced in vitro by free polysomes.

A comparison of acetylation in vitro of microsomal, homogenate, and Golgi fractions of rat liver

1988 ◽  
Vol 66 (10) ◽  
pp. 1152-1161 ◽  
Author(s):  
Hari Sambasivam ◽  
Robert K. Murray
Keyword(s):  
Golgi Apparatus ◽  
Rat Liver ◽  
Specific Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Sialic Acids ◽  
Acetyl Coa ◽  
Acetyltransferase Activity ◽  
Acetylneuraminic Acid

The activity of acetyltransferase was detected in the microsomal fraction of rat liver by incubation with [3H]acetyl-CoA and by analyses using sodium dodecyl sulfate – polyacrylamide gel electrophoresis. Endogenous membrane proteins of relatively high molecular weight were found to serve as substrates. Optimal conditions for assay of the enzyme were defined. A deacetylase activity was also detected, which was inhibited by 2 mM ethylenediaminetetraacetic acid. Further subfractionation disclosed that the acetyltransferase activity was most enriched in the Golgi fraction, in which its specific activity was some ninefold greater than in the total homogenate. The radioactive labelling of Golgi-associated proteins observed was relatively intense, exceeding that of histone and ribosomal proteins in the homogenate. Analysis of the acetylated Golgi fraction by two-dimensional electrophoresis revealed approximately 90 radioactive polypeptides. Various treatments demonstrated that a minimum of 80% of the incorporated radioactivity was present as derivatives of N-acetylneuraminic acid, principally N-acetyl-9-mono-O-acetylneuraminic acid (Neu5,9Ac2). The sialic acid O-acetyltransferase activity detected is thus probably identical to that reported by Varki and Diaz; the intense labelling of proteins reflects the ability of Golgi apparatus fractions to take up and concentrate acetyl-CoA. Protein-bound radioactive Neu5,9Ac2 was also detected in the medium of hepatocytes incubated with N-[3H]acetylmannosamine, demonstrating that these cells synthesize certain proteins containing acetylated sialic acids, some of which may be secreted. The data confirm that the Golgi apparatus is a major site of acetylation of protein-bound sialic acids in rat liver in vitro and provide new information showing that many glycoproteins undergo this particular type of modification.

Isolation and expression of cDNA clones for a rat liver asialoglycoprotein receptor

1986 ◽  
Vol 6 (6) ◽  
pp. 527-534
Author(s):  
Colin Watts
Keyword(s):  
Rat Liver ◽  
Protein Sequence ◽  
Wheat Germ ◽  
Asialoglycoprotein Receptor ◽  
Cdna Clones ◽  
Oligonucleotide Probes ◽  
Synthetic Oligonucleotide ◽  
Microsomal Membranes ◽  
Synthetic Oligonucleotides

cDNA clones for the major rat liver asialoglycoprotein (ASGP) receptor were isolated from a phage λgtl 1 library using synthetic oligonucleotide probes corresponding to two regions of the protein sequence. The longest clone obtained encoded all but the first 11 codons of the receptor. The cDNA was completed with synthetic oligonucleotides and was used to direct the synthesis of mRNA for the receptor in vitro. Subsequent translation in a wheat germ lysate produced authentic ASGP receptor which assembled correctly into microsomal membranes.

scholarly journals Preliminary characterization of the transcriptional and translational products of the Saccharomyces cerevisiae cell division cycle gene CDC28.

1982 ◽  
Vol 2 (4) ◽  
pp. 412-425 ◽  
Author(s):  
S I Reed ◽  
J Ferguson ◽  
J C Groppe
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
In Vitro Mutagenesis ◽  
Coding Region ◽  
Loop Analysis ◽  
Partial Digestion ◽  
Polyadenylic Acid

The CDC28 gene was subcloned from a plasmid containing a 6.5-kilobase-pair segment of Saccharomyces cerevisiae DNA YRp7(CDC28-3) by partial digestion with Sau3A and insertion of the resulting fragments into the BamHI sites of YRp7 and pRC1. Recombinant plasmids were obtained containing inserts of 4.4 and 3.1 kilobase pairs which were capable of complementing a cdc28(ts) mutation. R-loop analysis indicated that each yeast insert contained two RNA coding regions of about 0.8 and 1.0 kilobase pairs, respectively. In vitro mutagenesis experiments suggested that the smaller coding region corresponded to the CDC28 gene. When cellular polyadenylic acid-containing RNA, separated by agarose gel electrophoresis after denaturation with glyoxal and transferred to nitrocellulose membrane, was reacted with labeled DNA from the smaller coding region, and RNA species of about 1 kilobase in length was detected. Presumably, the discrepancy in size between the R-loop and electrophoretic determinations is due to a segment of polyadenylic acid which is excluded from the R-loops. By using hybridization of the histone H2B mRNAs to an appropriate probe as a previously determined standards, it was possible to estimate the number of CDC28 mRNA copies per haploid cell as between 6 and 12 molecules. Hybrid release translation performed on the CDC29 mRNA directed the synthesis of a polypeptide of 27,000 daltons, as determined by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. This polypeptide was not synthesized when mRNA prepared from a cdc28 nonsense mutant was translated in a parallel fashion. However, if the RNA from a cell containing the CDC28 gene on a plasmid maintained at a high copy number was translated, the amount of in vitro product was amplified fivefold.

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