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1.
EF-1a binds aminoacyl-tRNA to the ribosome with the hydrolysis of GTP; the complex facilitates the exchange of GDP for GTP to initiate another round of elongation. To examine the subunit structure of EF-1 and phosphorylation by protein kinase CKII, recombinant , , and subunits from rabbit were expressed in E. coli and the subunits were reconstituted into partial and complete complexes and analyzed by gel filtration. To determine the availability of the and subunits for phosphorylation by CKII, the subunits and the reconstituted complexes were examined as substrates for CKII. Formation of the nucleotide exchange complex increased the rate of phosphorylation of the subunit and reduced the Km, while addition of to or the complex inhibited phosphorylation by CKII. However, a had little effect on phosphorylation of . Thus, the and subunits in EF-1 were differentially phosphorylated by CKII, in that phosphorylation of was altered by association with other subunits, while the site on was always available for phosphorylation by CKII. From the availability of the subunits for phosphorylation by CKII and the composition of the reconstituted partial and complete complexes, a model for the subunit structure of EF-1 consisting of (22)2 is proposed and discussed.  相似文献   

2.
In the present report, we used serological, cellular, and restriction fragment length polymorphism (RFLP) to investigate the DR1 haplotype in the Israeli population. We describe an Israeli homozygous typing cell (HTC), HLA-DwLVA, which defines a new lymphocyte-activating determinant associated with Bw65, DR1 and distinct from Dwl. The parents of this donor, non-Ashkenazi Algerian Jews, are first cousins and share HLA-Cw8, Bw65, BfS, DR1, DQw1, DPw4. No specificity could be assigned to HLA-DwLVA using the 91 Ninth Workshop HTCs. Two families and forty unrelated DR1 individuals were studied with DwLVA and a panel of DR1/Dw1 HTCs. HLA-DwLVA showed segregation as a single determinant within families. This new specificity was present in 24 out of 40 (60%) unrelated DR1 individuals, indicating that in the Israeli population DwLVA is the main lymphocyte-defined determinant associated with the serologically defined DRI specificity, in contrast to non-Jewish Caucasoids where DR1 is significantly associated with Dw1. The vast majority of DwLVA-positive carriers were also Bw65 carriers, indicating that Bw65, DR1, DwLVA may represent a typical allele combination in the Israeli population. The RFLP analysis established the correlation of certain RFLPs with Dw1 and DwLVA. In addition, we describe a cluster of RFLPs that may correspond to a new Dw subtype associated with DR1, for which no serological and cellular reagents have been described so far.  相似文献   

3.
Classification of an industrial strain ofBacillus from which we have previously cloned an -amylase gene yielded ambiguous results with classical methods. However, positive identification asB. amyloliquefaciens was obtained by DNA analysis, by use of restriction enzyme fingerprinting and DNA hybridization analysis of genomic DNA, and by characterization of the purified -amylase.  相似文献   

4.
The sialyl-α2,6-lactosaminyl-structure: Biosynthesis and functional role   总被引:1,自引:0,他引:1  
Sialylation represents one of the most frequently occurring terminations of the oligosaccharide chains of glycoproteins and glycolipids. Sialic acid is commonly found ,3- or ,6-linked to galactose (Gal), ,6-linked to N-acetylgalactosamine (GalNAc) or ,8-linked to another sialic acid. The biosynthesis of the various linkages is mediated by the different members of the sialyltransferase family. The addition of sialic acid in ,6-linkage to the galactose residue of lactosamine (type 2 chains) is catalyzed by -galactoside ,6-sialyltransferase (ST6Gal.I). Although expressed by a single gene, this enzyme shows a complex pattern of regulation which allows its tissue- and stage-specific modulation. The cognate oligosaccharide structure, NeuAc,6Gal1,4GIcNAc, is widely distributed among tissues and is involved in biological processes such as the regulation of the immune response and the progression of colon cancer. This review summarizes the current knowledge on the biochemistry of ST6Gal.I and on the functional role of the sialyl-,6-lactosaminyl structure.  相似文献   

5.
In this study we present evidence indicating that GroE chaperonins mediate de novo protein folding of heterodimeric and monomeric luciferases under heat shock or sub-heat shock conditions in vivo. The effects of additional groESL and groEL genes on the bioluminescence of Escherichia coli cells expressing different bacterial luciferase genes at various temperatures were directly studied in cells growing in liquid culture. Data indicate that at 42° C GroESL chaperonins are required for the folding of the subunit polypeptide of the heterodimeric luciferase from the mesophilic bacterium Vibrio harveyi MAV (B392). In contrast, the small number of amino acid substitutions present in the luciferase subunit polypeptide from the thermotolerant V. harveyi CTP5 suppresses this requirement for GroE chaperonins, and greatly reduces interaction between the subunit polypeptide and GroEL chaperonin. In addition, GroESL are required for the de novo folding at 37° C of a MAV luciferase fusion polypeptide that is functional as a monomer. No such requirement for luciferase activity is observed at that temperature with a fusion of the CTP5 and subunit polypeptides, although GroE chaperonins can still mediate folding of the CTP5 fusion luciferase. Bacterial luciferases provide a unique system for direct observation of the effects of GroE chaperonins on protein folding and enzyme assembly in living cells. Furthermore, they offer a sensitive and simple assay system for the identification of polypeptide domains required for GroEL protein binding.  相似文献   

6.
The class II major histocompatibility complex antigens are cell-surface heterodimers consisting of an a and a chain. Cosmid cloning has shown that the three families of clas II antigens, DR, DQ, and DP, are encoded within the HLA-D region of chromosome 6 as a series of discrete gene clusters. The DP cluster contains two pairs of a and genes, one of which encodes the biochemically-defined DP antigen. In order to assess whether the other two genes, SXa and SX, are also expressed, potential coding regions have been subcloned and sequenced. The SX3 gene is shown to contain region closely homologous to all six exons of DP. A 1 bp deletion in the 2 exon, also observed for the SX4 allele, causes a translation frameshift, suggesting that SX is a pseudogene. However, all the other exons, as well as their splice sites and the putative promoter region, appear to be intact.  相似文献   

7.
Summary The relationship between the arrangement of cell events occurring in cambium in a definite configuration and the grain pattern of wood was investigated. Taking into consideration the growth activity of fusiform cell ends, a model of a migrating morphogenetic wave determining an event configuration was made. Waves of length =1 m for the periods T=2 years and T=3 years and waves of lengths =l m and =0.04 m for the period T=10 years were considered. On the model, events from successive annual rings, conventionally comprising 10 cell layers each, were summed. In this way, event maps were obtained. For wave =4 mm, the domain pattern on the modelled map was compatible with the grain pattern. The domain pattern for the wave =1 m was impossible to recreate because the wave migrated too fast. In this case, the pattern of event configuration, incompatible with the grain pattern, formed microareas, which were not domains.  相似文献   

8.
Summary The expression of the monocyte membrane glycoprotein CD14 was measured and related to the serum interferon (IFN) concentration in thirteen patients with disseminated cancer during treatment with human recombinant interferon (rIFN). The drug was administered by continuous subcutaneous infusion using an escalating dose schedule, starting at 50 µg/day or 100 µg/day and increasing weekly up to 600 µg/day, if tolerated. Treatment was continued at a mean maximal tolerated dose of 200 µg/day for a median duration of 43 days. Serum IFN concentration and monocyte CD14 antigen expression (immunofluorescence with the monoclonal antibody LeuM3 and fluorescence-activated cell sorting analysis) were determined weekly. The serum IFN concentration was positively correlated with the rIFN dose (P <0.05). Therapy induced a dose-dependant enhancement of CD14 antigen expression. The increase in mean CD14 fluorescence intensity was on average 60% after 3 weeks of treatment at a mean dose of 220 µg rIFN/day and was reversed after withdrawal of therapy. Patients with a rapidly rising serum IFN concentration (starting dose 100 µg/day) showed a smaller increment in CD14 fluorescence intensity than those with slowly rising serum IFN levels (starting dose 50 µg/day). Since rIFN is known to down-regulate CD14 antigen expression in vitro, monocytes from patients off therapy and from healthy volunteers were cultured with this cytokine. A similar decrease of CD14 fluorescence was observed in both groups. In patients several factors, such as IFN concentration, duration of drug effect and type of serum, were evaluated and could not explain the discrepant in vivo and in vitro findings. In conclusion, the monocyte marker CD14 was found to be differentially regulated by rIFN in vivo and in vitro. In vivo, secondary mediators, induced by rIFN and acting on a constantly renewed cell population, may contribute to the enhanced CD14 expression.  相似文献   

9.
Résumé Nous avons fait élever des larves d'Anergates atratulus par des ouvrières deMyrmica laevinodis à 22°C. Pour y parvenir, il n'est pas utile de faire hivernerensemble les larves d'Anergates et les ouvrières deMyrmica. La présence de larves autochtones n'empêche pas lesMyrmica d'élever des larves d'Anergates. Dans toutes les expériences lesMyrmica ont été soumises au fridavant de recevoir des larves d'Anergates. Aucune reine deMyrmica n'a été utilisée dans ces expériences.Sur les 64 larves d'Anergates que nous avons utilisées, 38 se sont transformées en imagos. C'est au début de l'adoption et au moment des métamorphoses que périrent la plupart des 26Anergates perdus. Les femelles vécurent en général 2 ou 3 jours et cherchèrent très tôt à quitter le nid natal. Les mâles vécurent 2 à 3 semaines.
Summary Larvae ofAnergates atratulus were experimentally reared by workers ofMyrmica laevinodis, at 22°C. An overwintering of both larvae ofAnergates and workers ofMyrmica is not necessary for the success of that experiment. The presence of larvae ofMyrmica does not keep theMyrmica from rearing larvae ofAnergates. The workers ofMyrmica have been cooled, in all the experiments, before receiving larvae ofAnergates. No queen ofMyrmica have been used in that experiments.38 of the 64 larvae ofAnergates used became imagos. Most of the 26 lostAnergates died at the beginning of the adoption and during the metamorphosis. The females lived generally 2 or 3 days and tried, very early, to leave their native nest. The males lived 2 or 3 weeks.

Anergates atratulus Myrmica laevinodis, 22 . bmecme Anergates Myrmica. Myrmica Anergates. Myrmica Anergates. Myrmica . 64 Anergates , 38 . 26 Anergates 2 3 . 2 3 .
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10.
This study determined whether the beneficial effects of exercise training on the diabetic heart previously observed are associated with alterations in ventricular myosin heavy chain (MHC) isoform composition. Diabetes was induced in rats by i.v. streptozotocin. Trained rats were run on a treadmill for 60 min/day, 27 m/min, 10% grade. After 10 wks, ventricular MHC isoenzyme protein composition was analyzed for MHC composition using gel electrophoresis. -MHC and -MHC mRNA were determined by Northern and slot blot hybridization techniques. Both protein and mRNA analyses indicated that sedentary control rats exhibited a predominance of -MHC. Sedentary diabetics exhibited a shift to -MHC. Exercise trained diabetic rats showed a predominance of -MHC. The results indicate that treadmill exercise training of diabetic rat does not prevent the diabetes-induced shift in MHC composition towards the -MHC isoform, thus it is unlikely that the beneficial effects of exercise training on the diabetic heart, previously shown, are due to a normalization of the myosin isoform composition.  相似文献   

11.
Summary Two specific -N-acetylglucosaminyltransferases involved in the branching and elongation of mucin oligosaccharide chains, namely, a 1,6 N-acetylglucosaminylsaminyltransferase that transfers N-acetylglucosamine from UDP-N-acetylglucosamine to Gal3GalNAc-Mucin to yield Gal3(GlcNAc6)GalNAc-Mucin and a 3-N-acetylglucosaminyl transferase that transfers N-acetylglucosamine from UDP-N-acetylglucosamine to Gal3(GlcNAC6)GalNAc-mucin to yield GlcNAc3Gal3 (GlcNAc6)GalNAc-Mucin were purified from the microsomal fraction of swine trachea epithelium. The 1,6-N-acetylglucosaminyltransferase was purified about 21,800-fold by procedures which included affinity chromatography on DEAE columns containing bound asialo Cowper's gland mucin glycoprotein with Gal1,3GalNAc side chains. The apparent molecular weight estimated by gel filtration was found to be about 60 Kd. The purified enzyme showed a high specificity for Gal1,3GalNAc chains and the most active substrates were mucin glycoproteins containing these chains. The apparent Km of the 6-glucosaminyltrans-ferase for Cowper's gland mucin glycoprotein containing Gal1,3GalNAc chains was 0.53 µM; for UDP-N-acetylglucosamine, 12 µM; and for Gal 1,3GalNAc NO2ø, 4 mM. The activity of the 6-glucosaminyltransferase was dependent on the extent of glycosylation of the Gal3GalNAc chains in Cowper's gland mucin glycoprotein.The best substrate for the partially purified 3-Glucosaminyltransferase was Cowper's gland mucin glycoprotein containing Gal1,3(GlcNAc6)GalNAc side chains. This enzyme showed little or no activity with intact sialylated Cowper's gland mucin glycoprotein or derivatives of this glycoprotein containing GalNAc or Gal1,3GalNAc side chains.The radioactive oligosaccharides formed by these enzymes in large scale reaction mixtures were released from the mucin glycoproteins by treatment with alkaline borohydride, isolated by gel filtration on Bio-Gel P-6 and characterized by methylation analysis and sequential digestion with exoglycosidases. The oligosaccharide products formed by the 6- and 3-glucosaminyltransferases were shown to be Gal3(GlcNAC6) GalNAc and GlcNAc3 Gal3(GlcNAC6)GalNAc respectively.Taken collectively, these results demonstrate that swine trachea epithelium contains two specific N-acetylglucosaminyltransferases which catalyze the initial branching and elongation reactions involved in the synthesis of O-linked oligosaccharide chains in respiratory mucin glycoproteins. The first enzyme a 6-glucosaminyltransferase converts Gal3GalNAc chains in mucin glycoproteins to Gal3(GlcNAc6)GalNAc chains. This product is the substrate for a second 3-glucosaminyltransferase which converts the Gal3(GlcNAc6)GalNAc chains to GlcNAc3Gal(GlcNAc6)GalNAc chains in the glycoprotein. The 3-glucosaminyltransferase did not utilize Gal3GalNAc chains as a substrate and this results in an ordered sequence of addition of N-acetylglucosamine residues to growing oligosaccharide chains in tracheal mucin glycoproteins.Abbreviations NeuNAc N-acetylneuraminic acid - GalNAcol N-acetylgalactosaminitol - CGMG Cowper's gland mucin glycoprotein - GalNAc-CGMG Cowper's gland mucin glycoprotein containing GalNAc side chains O-glycosidically linked to serine or threonine - Gal3GalNAc-CGMC Cowper's gland mucin glycoprotein containing Gal3GalNAc side chains - MES 2-(N-morpholino) Ethane Sulfonic acid - PBS Phosphate Buffered Saline  相似文献   

12.
The properties of the -2-l-fucosyltransferases in submaxillary gland preparations from blood group ABH secrefors and non-secretors were compared. The level of activity in the non-secretor gland homogenates amounted to about 5% only of that found in the secretor gland preparations. The enzymes from the two sources differed in solubility properties, charge and affinities for donor and acceptor substrates. The enzyme from secretor glands showed a preference for acceptors with Type 1 [d-galactosyl(1–3)-N-acetyl-d-glucosamine] structures whereas the enzyme from non-secretor glands had a preference for Type 2 [d-galactosyl(1–4)-N-acetyl-d-glucosamine] structures.These results demonstrate that expression of the secretor gene (Se) is associated with a molecular form of the -2-l-fucosyltransferase that is different from the species present in the same tissue when theSe gene is not expressed.  相似文献   

13.
Biology cannot accommodate all aspects of culture. Aspects of culture that a biological approach can take into account can be covered by the biological categories of phenotype and environment. There is no need to treat culture as a separate category. Attempts to elaborate biological explanations of cultural variation will meet with success only if biologists expand theories of development, and integrate them in evolutionary biology. The alternative — elaborating the idea of so-called cultural inheritance — makes little sense from a biological point of view.  相似文献   

14.
Zusammenfassung Die Lokalisierung von -Glucosidasen in Wurzeln der Kichererbse [Cicer arietinum (L.)] wurde in einem einstufigen fluoreszenz-optischen Verfahren mit 4-Methyl-umbelliferyl-D-glucosid untersucht. Am Beispiel der Kichererbse wird gezeigt, daß in polyphenolhaltigen Pflanzen herkömmliche Azokupplungsverfahren zur Glucosidaselokalisierung nicht anwendbar sind. Die mit der neuen Methode erhaltenen Ergebnisse decken sich im wesentlichen mit denen aus vergleichbaren Untersuchungen und zeigen, daß -Glucosidasen nicht vorhanden sind. Aryl--Glucosidasen wurden vorwiegend im äußeren Cortexbereich gefunden und nehmen mengenmäßig zur Wurzelspitze hin zu.
Localization of -glucosidase in roots ofCicer arietinum (L.) by a fluorescence technique
Summary The localization of -glucosidases in roots of garbanzo beans [Cicer arietinum (L.)] has been investigated by a one-step fluorescence optical procedure using 4-methylumbelliferyl--D-glucoside. It is shown that the well known azo-coupling test for the localization of glucosidases cannot be applied in polyphenol containing plants. The results obtained with the new method are comparable with those described in other investigations and further show that -glucosidases are absent from the root tissues investigated. The aryl--glucosidases were mainly detected in the outer region of the cortex and quantitatively increase towards the root tip.
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15.
The HLA-D region in nine Sardinian patients with classic Kaposi's sarcoma was studied with two restriction enzymes, Eco RI and Eco RV, and two cDNA probes, DR and DQ. A total of 41 polymorphic restriction fragments were identified. One, an 11.5 kb Eco RV DQ fragment, was present in three of the patients but in none of the controls; a second, an 8.0 kb Eco RV DR fragment, was present in six patients and all the controls. No single fragment was identified which was significantly over or under-represented in either group.  相似文献   

16.
Genotypes of Drosophila hydei having deficiencies of specific sections of X or Y chromosomal heterochromatin are characterized by heterogeneous rRNA gene numbers in their nonpolyploid organs. Depending on which sex heterochromatin portion is deleted, the rDNA amount in either brain or thoracic muscle cells or in both is increased threefold. This rDNA overreplication cannot be a compensation for a deficiency in ribosomal gene number, since the phenomenon also occurs in genotypes with a high initial rRNA gene numbers.  相似文献   

17.
Six tetrasaccharide fractions were isolated from shark cartilage chondroitin sulfate D by gel filtration chromatography followed by HPLC on an amine-bound silica column after exhaustive digestion with testicular hyaluronidase. Their structures were determined unambiguously by one- and two-dimensional 500 MHz1H NMR spectroscopy in conjunction with HPLC analysis of chondroitinase AC-II digests of the tetrasaccharides. One fraction was found to contain two tetrasaccharide components. All the seven tetrasaccharides shared the common core structure GlcA1-3GalNAc1-4GlcA1-3GalNAc with various sulfation profiles. Four were disulfated comprising of two monosulfated disaccharide units GlcA1-3GalNAc(4-sulfate) and/or GlcA1-3GalNAc(6-sulfate), whereas the other three were hitherto unreported trisulfated tetrasaccharides containing a disulfated disaccharide unit GlcA(2-sulfate)1-3GalNAc(6-sulfate) and a monosulfated disaccharide unit GlcA1-3GalNAc(4-or 6-sulfate). These sulfated tetrasaccharides were demonstrated to serve as appropriate acceptor substrates for serum -N-acetylgalactosaminyltransferase, indicating their usefulness as authentic oligosaccharide substrates or probes for the glycobiology of sulfated glycosaminoglycans.Abbreviations NFU National formulary unit - COSY correlation spectroscopy - HOHAHA homonuclear Hartmann-Hahn - 1D or 2D one- or two-dimensional - IdoA l-iduronic acid - GlcA d-gluco-4-enepyranosyluronic acid - Di-0S GlcA1-3GalNAc - Di-4S GlcA1-3GalNAc(4-sulfate) - Di-4S GlcA1-3GalNAc(4-sulfate) - Di-6S GlcA1-3GalNAc(6-sulfate) - Di-6S GlcA1-3GalNAc(6-sulfate) - Di-diS d GlcA(2-sulfate)1-3GalNAc(6-sulfate) - Di-diSE GlcA1-3GalNAc(4, 6-disulfate) - U G, U, 2S, 4S, and 6S represent GlcA, GalNAc, GlcA, 2-O-sulfate, 4-O-sulfate, and 6-O-sulfate, respectively  相似文献   

18.
R. Jarosch 《Protoplasma》1968,65(4):363-377
Zusammenfassung Es werden verschiedene Vorgänge an sehr zarten Pseudopodien beschrieben und mit Hilfe der an submikroskopischen Fibrillen (schraubig gebauten Mikrofibrillen und Mikroröhrchen der Elektronenmikroskopie) auftretenden Torsionsspannungen und Rotationen gedeutet.
On the dynamics of slender pseudopodia of bog amebae
Summary Different processes which occur on very slender pseudopods are described. They are interpreted with the help of torsional forces and revolutions of the submicroscopic fibrils (helical microfibrils and microtubules in electron microscopy).
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19.
Unravelling the factors that contribute to the formation and the stability of -sheet structure in peptides is a subject of great current interest. A -hairpin, the smallest -sheet motif, consists of two antiparallel hydrogen-bonded -strands linked by a loop region. We have performed a statistical analysis on protein -hairpins showing that the most abundant types of -hairpins, 2:2, 3:5 and 4:4, have characteristic patterns of 13C and 13C conformational shifts, as expected on the basis of their and angles. This fact strongly supports the potential value of 13C and 13C conformational shifts as a means to identify -hairpin motifs in peptides. Their usefulness was confirmed by analysing the patterns of 13C and 13C conformational shifts in 13 short peptides, 10–15 residues long, that adopt -hairpin structures in aqueous solution. Furthermore, we have investigated their potential as a method to quantify -hairpin populations in peptides.  相似文献   

20.
A defined set of oligosaccharides and glycopeptides containing -linked fucose were used to examine the specificity of the immobilized fucose-binding lectin Lotus tetragonolobus agglutinin (LTA1), also known as lotus lectin. Glycans containing the Lewis x determinant (Lex) Gal1-4[Fuc1-3]GlcNAc1-3-R were significantly retarded in elution from high density LTA-Emphaze columns. The lectin also bound the fucosylated lacdiNAc trisaccharide GalNAc1-4[Fuc1-3]GlcNAc. The lectin did not bind glycans containing either sialylLex or VIM-2 determinants, nor did it bind the isomeric Lea, Gal1-3[Fuc1-4]GlcNAc-R. Although 2-fucosyllactose Fuc1-2Gal1-4Glc) was retarded in elution from the columns, larger glycans containing the H-antigen Fuc1-2Gal1-3(4)GlcNAc-R interacted poorly with immobilized LTA. Our results demonstrate that immobilized LTA is effective in isolating glycans containing the Lex antigen and is useful in analyzing specific fucosylation of glycoconjugates. Abbreviations: LTA, Lotus tetragonolobus agglutinin; UEA-1, Ulex europaeus agglutinin-I; LNT, AAL, Aleuria aurantia agglutinin; Gal1-3GlcNAc1-3Gal1-3Glc; LNnT, Gal1-4GlcNAc1-3Gal1-3Glc; Lex, Lewis x antigen; Lea, Lewis a antigen; GDPFuc, guanosine 5-diphosphate--L-fucose  相似文献   

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