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1.
The CMP-N-acetylneuraminic acid (CMP-NeuNAc) synthetase gene of Neisseria meningitidis group B is located on a 2.3-kb EcoRI fragment within the cps gene cluster. Nucleotide sequence determination of the gene encoding the CMP-NeuNAc synthetase revealed a 515-bp open reading frame that can encode a 18.9-kDA protein. A computer data base scan revealed a 59.4% identity to the CMP-NeuNAc synthetase gene of E. coli K1. Enzymatic activity was confirmed in vitro and in vivo. Transformation of the CMP-NeuNAc defective E. coli K1 strain EV5 with the meningococcal CMP-NeuNAc synthetase could complement the defect in E. coli. 相似文献
2.
Ulrike Rosenfellner Franz Zehetner Martin H. Gerzabek 《Soil & Sediment Contamination》2009,18(6):685-687
Data from eight published studies were combined to show that the influence of traffic density on Pb contents in roadside soils increases with proximity to the road. 相似文献
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Exogenous long-chain fatty acids are readily taken up by unstimulated lymphocytes derived from the thymus of calves or rabbits and esterified to complex lipids, primarily phospholipids and triacylglycerols. Compared to saturated fatty acids, unsaturated fatty acids are incorporated preferentially. Furthermore, unsaturated fatty acids are transferred from triacylglycerols to phospholipids. The transfer cannot be observed with palmitic acid. With regard to individual phospholipid species, oleic acid and linoleic acid are found primarily in phosphatidylcholine. Arachidonic acid, however, is transferred to phosphatidylethanolamine and phosphatidylinositol as well. This suggests an arachidonic-specific transfer between individual phospholipids. Stimulation of the cells with the mitogen concanavalin A results in an enhanced incorporation of the fatty acids and an enhanced transfer from triacylglycerols to phospholipids. Triacylglycerols may thus be regarded as a labile intracellular storage pool that may be activated upon mitogenic stimulation. 相似文献
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Fluorescence polarization measurements with the probe 1,6-diphenyl-1,3,5-hexatriene (DPH) were performed to detect changes in the fluidity of plasma membranes from T-lymphocytes stimulated with mitogens. When the cells were incubated with succinyl-concanavalin A an increase in fluorescence polarization was observed. This, however, could be shown to be due to the interaction of the mitogen with the label DPH and did not reflect changes in the plasma membrane. In purified plasma membranes a decrease rather than an increase of fluorescence polarization was observed. 相似文献
7.
Regulation of prostaglandin synthesis by protein kinase C in mouse peritoneal macrophages. 总被引:2,自引:0,他引:2 下载免费PDF全文
Resident mouse peritoneal macrophages synthesized and released prostaglandins (PGs) when challenged with 12-O-tetradecanoylphorbol 13-acetate (TPA) or 1,2-dioctanoyl-sn-glycerol (DiC8). Both stimuli were found to activate Ca2+/phospholipid-dependent protein kinase C (PKC). 1-(5-Isoquinolinesulphonyl)-2-methylpiperazine ('H-7') and D-sphingosine, known to inhibit PKC by different mechanisms, were able to decrease the PKC activity of macrophages in a dose-dependent manner. Addition of either PKC inhibitor decreased PG synthesis and also the release of arachidonic acid (AA) from phospholipids induced by TPA or DiC8. Simultaneously TPA or DiC8 also decreased incorporation of free AA into membrane phospholipids of macrophages. AA incorporation could be restored, however, by pretreatment with the PKC inhibitors. Our results demonstrate an involvement of PKC in the regulation of PG synthesis in mouse peritoneal macrophages and provide further evidence that reacylation of released fatty acids may be an important regulatory step. 相似文献
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Characterization of the interleukin-1-induced tyrosine phosphorylation of a 41-kDa plasma membrane protein of the human tumor cell line K 562 总被引:1,自引:0,他引:1
A 41-kDa protein, which was specifically phosphorylated upon incubation with natural purified murine interleukin 1, was recently identified by us [Martin, M., Lovett, D. H. and Resch, K. (1986) Immunobiology 171, 165-169] in highly purified plasma membranes from the human tumor cell line K 562. An in vitro assay was used to investigate and characterize the phosphorylation induced by interleukin 1, possibly involved in signal transduction and generation. Plasma membranes were incubated with radiolabeled ATP in the presence of purified natural murine interleukin 1, or recombinant human interleukin 1 alpha and the pattern of phosphoproteins was studied after separation by SDS/PAGE and subsequent autoradiography. A 41-kDa protein (pp41) was specifically phosphorylated on a tyrosine residue in the presence of interleukin 1 in a dose- and time-dependent manner. The protein showed a weak background phosphorylation in the absence of monokine. Phosphorylation took place very efficiently at 0 degrees C, whereas phosphatases were not active at that temperature. At 37 degrees C, a rapid dephosphorylation was observed which was inhibited specifically by Zn2+ and vanadate. The interleukin-1-specific induction of the phosphorylation could also be observed after detergent solubilization of the plasma membranes. Affinity labeling with an ATP analogue revealed an ATP-binding and cleaving site at 41 kDa. Interleukin 1 did not induce the phosphorylation of p41 in plasma membranes obtained from a subclone of K 562, which did not respond to interleukin 1 with growth inhibition, as was reported recently for the K 562 mother line [Lovett, D. H., Kozan, B., Hadam, M., Resch, K. and Gemsa, D. (1986) J. Immunol. 136, 340-347]. These data suggest that the interleukin-1 receptor is functionally linked to a protein-tyrosine kinase, which is implicated in its biological function. 相似文献
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Summary A new genetic polymorphism of a human serum glycoprotein, the inter--trypsin-inhibitor (ITI), has been demonstrated by population and family studies. Sera were examined after neuraminidase treatment by isoelectric focusing on agarose gels followed by immunoblotting or by immunfixation with specific ITI-antiserum. Using this method, three common ITI phenotypes 1, 1–2 and 2, as well as two further rare ITI types 1–3 and 2–3 were disclosed. Genetically, these phenotypes are controlled by three allelic genes that determine a total of six phenotypes. These alleles are designated ITI*1, ITI*2 and ITI*3. The homozygous form of the third allele ITI*3 has not been found, as yet. The frequencies of ITI were examined in two population samples from Southern Germany (n=248) and from Tyrol, Austria (n=124). The gene frequencies of the common alleles ITI*1 and ITI*2 were 0.575 and 0.417, respectively, in Southern Germany, and 0.577 and 0.423, respectively, in Tyrol, Austria. The third allele ITI*3 was found only in the sample from Southern Germany, thus far, and was calculated to be 0.008. 相似文献
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