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1.
Rita Padányi Yuning Xiong Géza Antalffy Krisztina Lór Katalin Pászty Emanuel E. Strehler ágnes Enyedi 《The Journal of biological chemistry》2010,285(41):31704-31712
The membrane localization of the plasma membrane Ca2+-ATPase isoform 2 (PMCA2) in polarized cells is determined by alternative splicing; the PMCA2w/b splice variant shows apical localization, whereas the PMCA2z/b and PMCA2x/b variants are mostly basolateral. We previously reported that PMCA2b interacts with the PDZ protein Na+/H+ exchanger regulatory factor 2 (NHERF2), but the role of this interaction for the specific membrane localization of PMCA2 is not known. Here we show that co-expression of NHERF2 greatly enhanced the apical localization of GFP-tagged PMCA2w/b in polarized Madin-Darby canine kidney cells. GFP-PMCA2z/b was also redirected to the apical membrane by NHERF2, whereas GFP-PMCA2x/b remained exclusively basolateral. In the presence of NHERF2, GFP-PMCA2w/b co-localized with the actin-binding protein ezrin even after disruption of the actin cytoskeleton by cytochalasin D or latrunculin B. Surface biotinylation and fluorescence recovery after photobleaching experiments demonstrated that NHERF2-mediated anchorage to the actin cytoskeleton reduced internalization and lateral mobility of the pump. Our results show that the specific interaction with NHERF2 enhances the apical concentration of PMCA2w/b by anchoring the pump to the apical membrane cytoskeleton. The data also suggest that the x/b splice form of PMCA2 contains a dominant lateral targeting signal, whereas the targeting and localization of the z/b form are more flexible and not fully determined by intrinsic sequence features. 相似文献
2.
Katalin Rostas Prakash Rao Sista John Stanley Desh Pal S. Verma 《Molecular & general genetics : MGG》1984,197(2):230-235
Summary We report here successful mutagenesis with Transposon Tn5 of three slow-growing strains of Rhizobium japonicum USDA 122, 61A76, USDA 74 and one fast-growing strain, USDA 191. Strains were chosen as representatives of different DNA homology and serogroups of this divergent species, which effectively nodulate North American soybean cultivars. The source of Tn5 was the suicide plasmid pGS9, which possesses broad host range N-type transfer genes in a narrow host range p15A replicon. The selection of Tn5 mutants was facilitated by the expression of the Tn5 encoded streptomycin gene in R. japonicum. Kanamycin and streptomycin resistant colonies appeared from interspecific crosses with E. coli at optimal frequencies of 10-6 for R. japonicum USDA 61A76 and USDA 191 and 5x10-7 for R. japonicum USDA 122 and USDA 74. Altogether, 6550 Tn5 mutants were isolated in USDA 122 and 61A76, and a small number from USDA 74 and USDA 191. Colony hybridization showed that all tested mutants of 61A76 and USDA 122 contained Tn5. Physical analysis of total DNAs from representative numbers of USDA 122, 61A76 and USDA 191 mutants revealed that each of them carried one copy of the transposon integrated randomly in the genome. This was also true for most USDA 74 mutants. Screening of mutants for auxotrophy showed frequencies of 0.2% for USDA 122 and 0.08% for 61A76. Several symbiotically defective mutants were identified on plants, Glycine soja and G. max. 相似文献
3.
Dr. Hans-Joachim Gabius Katalin Vehmeyer Reinhild Engelhardt Gerd A. Nagel Friedrich Cramer 《Cell and tissue research》1986,246(3):515-521
Summary A tumor model system of clones of myeloproliferative sarcoma virus (MPV)-transformed rat fibroblasts (NRK) with different growth properties and metastatic potential was studied. The relationship between metastatic behavior and composition of carbohydrate-binding proteins (lectins) was analyzed by affinity chromatography. The metastatic variant differs qualitatively from its parental clone in the presence of galactoside-binding proteins at apparent molecular weights of 80 kDa, 70 kDa, 22 kDa, 18 kDa and 16 kDa and of a fucose-binding protein at apparent molecular weight of 42 kDa. The -glucosyl-binding proteins at apparent molecular weights of 67 kDa and 53 kDa and a galactoside-binding protein of apparent molecular weight of 34 kDa, however, are not detectable in the metastatic variant in comparison to its parental clone. In this respect the parental clone shows closer resemblance to the clone 5–8#1 with different growth properties and low metastatic potential than to its own metastatic variant. Furthermore, only the parental clone has a melibiose- and a mannan-binding protein of an apparent molecular weight of 64 kDa and 14 kDa, respectively. Rosette formation as model system for intercellular interaction reveals differences in the inhibition pattern with sugar between the two clones 5–8#1 and 5–20#20, whereas the metastatic variant 5–20#20 (s) exhibits drastically reduced capability to form rosettes. Initial experiments demonstrate the feasibility of drug targeting to transformed fibroblasts via carbohydrate-binding proteins. 相似文献
4.
Michael J. Sadowsky Katalin Rostas Prakash R. Sista Howard Bussey Desh Pal S. Verma 《Archives of microbiology》1986,144(4):334-339
Four histidine auxotrophs of Bradyrhizobium japonicum strain USDA 122 were isolated by random transposon Tn5 mutagenesis. These mutants arose from different, single transposition events as shown by the comparison of EcoRI and XhoI-generated Tn5 flanking sequences of genomic DNA. The mutants grew on minimal medium supplemented with l-histidine or l-histidinol but failed to grow with l-histidinol phosphate. While two of the muants were symbiotically defective and did not form nodules on Glycine max cvs. Lee and Peking and on Glycine soja, the other two mutants were symbiotically competent. Reversion to prototrophy occurred at a frequency of about 10-7 on growth medium without added antibiotics, but prototrophs could not be isolated from growth medium containing 200 g/ml kanamycin and streptomycin. The prototrophic revertants formed nodules on all the soybean cultivars examined. When histidine was supplied to the plant growth medium, both nodulation deficient mutants formed effective symbioses. On histidine unamended plants, nodules were observed infrequently. Three classes of bacterial colonies were isolated from such infrequent nodules: class 1 were kanamycin resistant-auxotrophs; class 2 were kanamycin sensitive-prototrophs; and class 3 were kanamycin-sensitive auxotrophs. Our results suggest that two Tn5 insertion mutations in B. japonicum leading to histidine auxotrophy, affect nodulation in some way. These mutations are in regions that show no homology to the Rhizobium meliloti common nodulation genes. 相似文献
5.
Ernő Berényi Péter Surányi Katalin Pálóczi Gyula Szegedi 《Cancer immunology, immunotherapy : CII》1986,21(2):164-166
Summary The percentage and absolute number of lymphocytes and Leu 7+ cells were significantly lower in HD even in active stages. There was no significant difference in the percentage of LGL between the three groups (control, active HD, inactive HD), however, because of differences in counts of lymphocytes the absolute number of LGL was significantly lower in HD even in the active group than that in healthy controls. The absolute count of LGL and Leu 7+ cells in patients in remission was significantly higher than that in active HD. Natural cytotoxicity against K-562 cells was also significantly lower in active patients in comparison with controls, while the percentage of cytotoxicity was slightly but not significantly higher in patients in remission than that in the active group. A positive correlation was observed between all the three examined parameters both in controls and in patients with active and inactive HD. 相似文献
6.
Protochlorophyll (PChl) forms were performed in Triton X-100 detergent micelles. The concentration of Triton X-100 was 7·10?4 M (above the critical micellar concentration); the concentration of PChl varied between 1.6·10?5 and 1.8·10?4 M. Absorption, fluorescence and circular dichroism (CD) spectra were registered. The absorption spectra were resolved into Gaussian components by computer analysis. PChl forms with absorption bands at 632–634, 638, 652–654, 663–664, 668 and 676 nm and with fluorescence emission bands at 634–636, 640–644, 652–655, 677–678, 686 and 694–696 nm were observed in micellar solutions of different PChl concentrations. The CD spectra showed a strong dependence on the concentration of PChl: positive CD signals or positive Cotton effects were observed in the vicinity of 650 nm. The intensity of these signals increased in parallel with increasing concentration of PChl. No CD signals were found in the region of the longer wavelength absorption bands. These data show that the PChl exists in many different forms in this system, and the spectroscopic properties of these forms are determined by different molecular interactions viz., interactions of PChl with Triton X-100 or water molecules and/or by the aggregation of PChl. 相似文献
7.
Iron-induced lipid peroxidation and inhibition of dopamine synthesis in striatum synaptosomes 总被引:4,自引:0,他引:4
Crude striatum synaptosomes (P2 fraction) from Fisher 344 female rats were incubated in the presence of ADP-chelated Fe3+ (0.5–50 M) and ascorbate (250 M). Intrasynaptosomal conversion of tyrosine to dopamine (DA) was measured by14CO2 evolution froml-[1-14C]tyrosine in the absence of added cofactors and DOPA decarboxylase. Malondialdehyde (MDA) was measured as an index of lipid peroxidation. A concentration-dependent inhibition of DA synthesis by ADP-Fe3+/ascorbate was found with 50% inhibition occurring at 2.5 M Fe3+ concentration. This was accompanied by marked accumulation of MDA. Ascorbate or ADP alone did not affect DA synthesis and ADP-Fe3+ in the absence of exogenous ascorbate was effective only above 25 M. Exogenously added MDA did not inhibit DA synthesis. Purified synaptosomes were isolated from peroxidized and control P2 fractions using sucrose gradients. Membrane microviscosity of the purifled synaptosomes was assessed by nitroxyl spin labels of stearic acid using electron paramagetic resonance techniques. There was a significant increase in membrane microviscosity as a result of ADP-Fe3+/ascorbate induced peroxidation. Maleimide nitroxide spin-label binding to protein sulhydryls was significantly modified by peroxidation of striatum synaptosomes. The weakly immobilized component of the sulhydryl spin-label (w) was drastically decreased whereas the strongly immobilized component (s) was modified less, thus leading to a marked reduction of w/s ratio. The exposure of striatum synaptosomes to the peroxidizing system resulted in a significant increase in total iron and in a 25% decrease in protein sulhydryl content. It is concluded that ironinduced damage to the DA synthetic system is mediated by alterations of the structural properties of nerve ending membranes. 相似文献
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10.
Small doses of β-endorphin (10?11?10?5M) decrease corticosterone production of zona fasciculata cells but fail to influence steroid production of zona glomerulosa cells. 10?4M β-endorphin increases corticosterone production of both zones. The stimulating effect of ACTH on zona fasciculata corticosterone- and zona glomerulosa aldosterone production was decreased by β-endorphin (10?9?10?7M). Conclusion: β-endorphin might modulate both basal and ACTH stimulated corticosterone secretion. 相似文献