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31.
32.
Giardina P Autore F Faraco V Festa G Palmieri G Piscitelli A Sannia G 《Applied microbiology and biotechnology》2007,75(6):1293-1300
The subfamily of POXA3 laccase isoenzymes produced by the fungus Pleurotus ostreatus has been characterized as an example of the complexity and heterogeneity of fungal isoenzyme patterns. Two isoenzymes, POXA3a
and POXA3b, were previously purified, exhibiting an unusual heterodimeric structure composed of a large (67 kDa) and a small
(18 or 16 kDa) subunit. A unique gene encodes the large subunit of both POXA3a and POXA3b, but alternative splicing produces
two variants—differing for an insertion of four amino acids—for each isoenzyme. Two genes encoding POXA3a and POXA3b small
subunits have been identified, and the corresponding amino acid sequences show only two amino acid substitutions. The 18-
and 16-kDa subunits of both POXA3a and POXA3b differ for N-glycosylation at Asn150 of the 16-kDa subunit. The POXA3 large subunit 3D model allows us to highlight peculiarities of this
molecule with respect to the laccases whose 3D structures are known. 相似文献
33.
Maria Carafa Giuseppe Lucania Emilia Marchei Vincenza Dolo Maria Giammatteo Maria Rosaria Torrisi Eleanora Santucci Antonio Pavan 《Biotechnic & histochemistry》1999,74(2):77-84
We analyzed the binding and fusogenic properties of surfactant vesicles (SVs), composed of ionic and nonionic surfactants and cholesterol, with the surface of different human lymphoid cells. The influence of charge on SVs-cell interaction was evaluated by monitoring the presence of fluorescent sodium calcein artificially entrapped in the vesicles using optical fluorescence microscopy and laser scanning confocal microscopy. Our results clearly indicate that only negatively charged vesicles bind and fuse with the plasma membrane of human lymphoid cells, and the number of SVs bound to the cell surface was variable among the positive cells. Thin section electron microscopy illustrated that the fusogenic events of SVs with the cell plasma membrane mostly occurred at smooth and nonvillous regions of the cell surface. Taken together, our results suggest that binding and fusion of SVs with the cell plasma membrane might be dependent on interactions with specific membrane components that preferentially recognize negatively charged SVs. 相似文献
34.
Virgilio F Sciarrillo R Laforgia V Varano L 《Journal of experimental zoology. Part A, Comparative experimental biology》2003,296(2):137-142
Although endothelins were originally discovered as peptides with vasoconstrictor activity, recent studies have indicated a number of endothelin (ET) induced hormonal functions in various tissues. We have studied the interaction of ET-1 with thyroid gland of the lizard Podarcis sicula. The effects of ET-1 administration on the plasma levels of the thyroid hormones (T3 and T4) and TSH were stimulatory. Morphological changes in the thyroid after treatment with ET-1 were also detected: the height of the epithelial cells slightly increased and the apical surface acquired microvilli protruding into the follicular lumen. The colloid filled up the lumen and showed a rich peripheral vacuolation. In conclusion, a modulatory role in the control of the reptilian thyroid gland is suggested for ET-1. This is the first report on the interaction of ET-1 with the thyroid gland of reptilian. 相似文献
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Catania MV Giuffrida R Seminara G Barbagallo G Aronica E Gorter JA Dell'Albani P Ravagna A Calabrese V Giuffrida-Stella AM 《Neurochemical research》2003,28(3-4):607-615
Neuronal nitric oxide synthase (nNOS) is a constitutively expressed and calcium-dependent enzyme. Despite predominantly expressed in neurons, nNOS has been also found in astrocytes, although at lower expression levels. We have studied the regulation of nNOS expression in cultured rat astrocytes from cortex and spinal cord by Western blotting and immunocytochemistry. nNOS was not detectable in cultured astrocytes grown in serum-containing medium (SCM), but was highly expressed after serum deprivation. Accordingly, calcium-dependent NOS activity and both intracellular nitrite levels and nitrotyrosine immunoreactivity after glutamate stimulation were higher in serum-deprived astrocytes than in cells grown in SCM. Serum deprivation induced a modification of astrocytes morphology, from flat to stellate. nNOS upregulation was also observed in reactive astrocytes of rat hippocampi after electrically induced status epilepticus, as demonstrated by double-labeling experiments. Thus, nNOS upregulation occurs in both in vitro stellate and in vivo reactive astrocytes, suggesting a possible involvement of glial nNOS in neurological diseases characterized by reactive gliosis. 相似文献
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Morozzo Della Rocca B Miniero DV Tasco G Dolce V Falconi M Ludovico A Cappello AR Sanchez P Stipani I Casadio R Desideri A Palmieri F 《Molecular membrane biology》2005,22(5):443-452
The structural and dynamic properties of the oxoglutarate carrier were investigated by introducing a single tryptophan in the Trp-devoid carrier in position 184, 190 or 199 and by monitoring the fluorescence spectra in the presence and absence of the substrate oxoglutarate. In the absence of substrate, the emission maxima of Arg190Trp, Cys184Trp and Leu199Trp are centered at 342, 345 and 348 nm, respectively, indicating that these residues have an increasing degree of solvent exposure. The emission intensity of the Arg190Trp and Cys184Trp mutants is higher than that of Leu199Trp. Addition of substrate increases the emission intensity of Leu199Trp, but not that of Cys184Trp and Arg190Trp. A 3D model of the oxoglutarate carrier was built using the structure of the ADP/ATP carrier as a template and was validated with the experimental results available in the literature. The model identifies Lys122 as the most likely candidate for the quenching of Trp199. Consistently, the double mutant Lys122Ala-Leu199Trp exhibits a higher emission intensity than Leu199Trp and does not display further fluorescence enhancement in response to substrate addition. Substitution of Lys122 with Cys and evaluation of its reactivity with a sulphydryl reagent in the presence and absence of substrate confirms that residue 122 is masked by the substrate, likely through a substrate-induced conformational change. 相似文献
39.
Prions are defined as infectious agents that comprise only proteins and are responsible for transmissible spongiform encephalopathies (TSEs)--fatal neurodegenerative diseases that affect humans and other mammals and include Creutzfeldt-Jacob disease in humans, scrapie in sheep and bovine spongiform encephalopathy in cattle. Prions have been proposed to arise from the conformational conversion of the cellular prion protein PrP(C) to a misfolded form termed PrP(Sc) that precipitates into aggregates and fibrils. The conversion process might be triggered by interaction of the infectious form with the cellular form or it might result from a mutation in the gene encoding PrP(C). Exactly how and where in the cell the interaction and the conversion of PrP(C) to PrP(Sc) occur, however, remain controversial. Recent studies have shed light on the intracellular trafficking of PrP(C), the role of protein mis-sorting and the cellular factors that are thought to be required for the conformational conversion of prion proteins. 相似文献
40.
Elena Turola Salvatore Petta Ester Vanni Fabiola Milosa Luca Valenti Rosina Critelli Luca Miele Livia Maccio Vincenza Calvaruso Anna L. Fracanzani Marcello Bianchini Nazarena Raos Elisabetta Bugianesi Serena Mercorella Marisa Di Giovanni Antonio Craxì Silvia Fargion Antonio Grieco Calogero Cammà Franco Cotelli Erica Villa 《Disease models & mechanisms》2015,8(9):1037-1046