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排序方式: 共有254条查询结果,搜索用时 15 毫秒
1.
S. K. Podder A. Chakraborti K. Vijayalakshmi P. Lalit Kumar Singh 《Journal of biosciences》1987,11(1-4):495-502
To examine how surface Potential controls the reactivity of glycoconjugates at cell surface, the interaction of galactose-sPecific
lectinse.g. peanut agglutinin,Ricinus cummunis agglutinin with liPosomes bearing asialo GM1 were studied in the Presence of varying amount of ganglioside mixture, GMn. The Presence of 5% GMn causes comPlete slowing down of PreciPitin reaction and thereby make carbohydrate moiety of asialo GM1 comPletely inaccessiblei.e. ‘cryPtic’. In contrast the Presence of 1–2% GMn enhances the aPParent rate and amPlitude of the PreciPitin reaction as surface Potential becomes more negative. The relevance
of the findings has been discussed in relation to the exPression and involvement of the cell-surface sialic acid residues
during develoPment and differentiation. 相似文献
2.
The large family of signal transducing proteins known as G proteins are heterotrimers that dissociate into an independent α-subunit and βγ-subunit complex after ligand binding or other stimulation. For Gα, at least 30 distinct sequences representing 10 different classes have been identified. On the other hand, cDNAs for only three Gβ-subunit genes have been isolated so far. All three of the Gβ genes have been chromosomally mapped in the human, but only two in the mouse. Using a human retinal cDNA for the third G protein β-subunit, we have mapped the corresponding gene, termed Gnb-3, to mouse Chromosome 6 with somatic cell hybrids and have positioned it distal to but near the marker Raf-1 by analysis of the progeny of three genetic crosses. 相似文献
3.
Sajal Chakraborti Sandip K. Batabyal John R. Michael Tapati Sanyal 《Molecular and cellular biochemistry》1994,130(2):121-127
Exposure of rabbit pulmonary arterial smooth muscle cells to 10 M of the calcium ionophore A23187 dramatically stimulates cell membrane-associated phospholipase A2 activity and arachidonic acid release. In addition, A23187 also enhances cell membrane-associated serine esterase activity. Serine esterase inhibitors phenylmethylsulfonylfuoride and diisopropyl fluorophosphate prevent the increase in serine esterase and phospholipase A2 activities and arachidonic acid release caused by A23187. A23187 still stimulated serine esterase and phospholipase A2 activities and arachidonic acid release in cells pretreated with nominal Ca2+ free buffer. Treatment of the cell membrane with A23187 does not cause any appreciable change in serine esterase and phospholipase A2 activities. Pretreatment of the cells with actinomycin D or cycloheximide did not prevent the increase in the cell membrane associated serine esterase and phospholipase A2 activities, and arachidonic acid release caused by A23187. These results suggest that (i) a membrane-associated serine esterase plays an important role in stimulating the smooth muscle cell membrane associated phospholipase A2 activity (ii) in addition to the presence of extracellular Ca2+, release of Ca2+ from intracellular storage site(s) by A23187 also appears to play a role in stimulating the cell membrane-associated serine esterase and phospholipase A2 activities, and (iii) the increase in the cell membrane-associated serine esterase and phospholipase A2 activities does not appear to require new RNA or protein synthesis.Abbreviations A23187
calcium ionophore
- AA
arachidonic acid
- PMSF
phenylmethyl sulfonylfuoride
- DFP
diisopropyl-fluorophosphate
- DMEM
Dulbecco's modified Eagles medium
- FCS
fetal calf serum
- PBS
phosphate buffered saline
- HBPS
Hank's buffered physiological saline
- PLA2
phospholipase A2 相似文献
4.
The antimicrobial activities of six withanolide compounds are compared. 相似文献
5.
Exposure of rabbit pulmonary arterial smooth muscle cells to the calcium ionophore A23187, dose-dependently stimulates arachidonic acid (AA) release and phospholipase A2 (PLA2) activity. The protein kinase C (PKC) inhibitor, sphingosine does not prevents AA release and PLA2 activity caused by low doses of A23187. In contrast, sphingosine markedly prevents AA release and PLA2 activity caused by higher doses of A23187. PKC activity profile indicates that treatment of the cells with low doses of A23187 does not cause significant alteration of PKC translocation from cytosol to membrane whereas higher concentrations of the ionophore dose-dependently enhance PKC translocation from cytosol to membrane in the smooth muscle cells. 相似文献
6.
Plasmid-encoded degradation of p-nitrophenol and 4-nitrocatechol by Arthrobacter protophormiae 总被引:4,自引:0,他引:4
Chauhan A Chakraborti AK Jain RK 《Biochemical and biophysical research communications》2000,270(3):733-740
Arthrobacter protophormiae strain RKJ100 is capable of utilizing p-nitrophenol (PNP) as well as 4-nitrocatechol (NC) as the sole source of carbon, nitrogen and energy. The degradation of PNP and NC by this microorganism takes place through an oxidative route, as stoichiometry of nitrite molecules was observed when the strain was grown on PNP or NC as sole carbon and energy sources. The degradative pathways of PNP and NC were elucidated on the basis of enzyme assays and chemical characterization of the intermediates by TLC, GC, (1)H NMR, GC-MS, UV spectroscopy, and HPLC analyses. Our studies clearly indicate that the degradation of PNP proceeds with the formation of p-benzoquinone (BQ) and hydroquinone (HQ) and is further degraded via the beta-ketoadipate pathway. Degradation of NC involved initial oxidation to generate 1,2,4-benzenetriol (BT) and 2-hydroxy-1,4-benzoquinone; the latter intermediate is then reductively dehydroxylated, forming BQ and HQ, and is further cleaved via beta-ketoadipate to TCA intermediates. It is likely, therefore, that the same set of genes encode the further metabolism of HQ in PNP and NC degradation. A plasmid of approximately 65 kb was found to be responsible for harboring genes for PNP and NC degradation in this strain. This was based on the fact that PNP(-) NC(-) derivatives were devoid of the plasmid and had simultaneously lost their capability to grow at the expense of these nitroaromatic compounds. 相似文献
7.
8.
Pratim Chakraborti Ayan Roy Sunanda Mandal Subhasish Mukhopadhyay 《Journal of biomolecular structure & dynamics》2013,31(11):2330-2346
Our environment is stressed with a load of heavy and toxic metals. Microbes, abundant in our environment, are found to adapt well to this metal-stressed condition. A comparative study among five Cupriavidus/Ralstonia genomes can offer a better perception of their evolutionary mechanisms to adapt to these conditions. We have studied codon usage among 1051 genes common to all these organisms and identified 15 optimal codons frequently used in highly expressed genes present within 1051 genes. We found the core genes of Cupriavidus metallidurans CH34 have a different optimal codon choice for arginine, glycine and alanine in comparison with the other four bacteria. We also found that the synonymous codon usage bias within these 1051 core genes is highly correlated with their gene expression. This supports that translational selection drives synonymous codon usage in the core genes of these genomes. Synonymous codon usage is highly conserved in the core genes of these five genomes. The only exception among them is C. metallidurans CH34. This genomewide shift in synonymous codon choice in C. metallidurans CH34 may have taken place due to the insertion of new genes in its genomes facilitating them to survive in heavy metal containing environment and the co-evolution of the other genes in its genome to achieve a balance in gene expression. Structural studies indicated the presence of a longer N-terminal region containing a copper-binding domain in the cupC proteins of C. metallidurans CH3 that helps it to attain higher binding efficacy with copper in comparison with its orthologs. 相似文献
9.
10.
The detailed composition and structure of the Caenorhabditis elegans surface are unknown. Previous genetic studies used antibody or lectin binding to identify srf genes that play roles in surface determination. Infection by Microbacterium nematophilum identified bus (bacterially unswollen) genes that also affect surface characteristics. We report that biofilms produced by Yersinia pestis and Y. pseudotuberculosis, which bind the C. elegans surface predominantly on the head, can be used to identify additional surface-determining genes. A screen for C. elegans mutants with a biofilm absent on the head (Bah) phenotype identified three novel genes: bah-1, bah-2, and bah-3. The bah-1 and bah-2 mutants have slightly fragile cuticles but are neither Srf nor Bus, suggesting that they are specific for surface components involved in biofilm attachment. A bah-3 mutant has normal cuticle integrity, but shows a stage-specific Srf phenotype. The screen produced alleles of five known surface genes: srf-2, srf-3, bus-4, bus-12, and bus-17. For the X-linked bus-17, a paternal effect was observed in biofilm assays. 相似文献