1,720,993 research outputs found
In-vitro dual binding activity of a evolutionarily related subgroup of hnRNP proteins
No full textThe wide family of heterogeneous nuclear ribonucleoproteins (hnRNPs) comprises members that interact with single-stranded
nucleic acids. On the basis of their structure, some of them are characterised by a tandem RNA-binding domain (RBD) and a
glycine-rich C-terminus, showing a high degree of homology. Recently, we have isolated some proteins belonging to this group
that interact with single-stranded cytosine-block telomeric DNA. The aim of the present investigation is to better characterise the
relationship of some structural features shared by these proteins and their in-vitro interaction with the telomeric type sequences.
We analysed the in-vitro binding properties of some of these components toward both single-stranded telomeric motifs. Using
deletion mutants, the relationship between cytosine-rich motif binding activity and the structural features of one of these proteins
is further characterized. This binding activity appears to be related to a subgroup of the 2xRBD+Glycine rich hnRNP, suggesting
functionally distinct properties of these proteins, in agreement with their evolutionary relationship. (Mol Cell Biochem 268:
121–127, 2005
Novel approaches for scanning near-field optical microscopy imaging of oligodendrocytes in culture
No full textNewborn rat oligodendrocyte cultures were investigated by scanning near-field optical microscope (SNOM), a versatile new tool able to map cell membranes in 3D and simultaneously obtain images of the cytoplasm. Topography, error, transmission and reflection signals were acquired to describe cell morphology with nanometer-scale resolution. Oligodendrocytes were studied as a model because their extensive membrane processes (typical of their physiological role in myelination) made them particularly suitable to test the sensitivity of the new method. Furthermore, we combined a classical histochemical method with SNOM, to identify specific intracellular proteins at high definition. In particular, with this technique, cytoskeleton elements of oligodendrocytes, such as microtubules, were observed with tubulin antibodies. Images obtained with SNOM were also compared with those from conventional scanning electron microscopy (SEM) and optical microscopy. Our results showed that SNOM allowed to o
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mast cell activation by myelin through scavenger receptor.
No full textA role for mast cells (MC) in the pathogenesis of multiple sclerosis (MS) has been suggested, based on the analysis of human lesions and on an
animal model of the disease (EAE). What role MC play in the development of MS is not well understood. We hypothesized that the link
connecting MC with demyelinating diseases may be represented by their interaction with myelin. Here we show that myelin can activate mast
cells. This process could be a key event in the mast cell function required for inducing EAE in mice and possibly in MS in ma
Characterization of electrogenic bromosulfophthalein transport in carnation petal microsomes and its inhibition by antibodies against bilitranslocase
No full textBilitranslocase is a rat liver plasma membrane carrier, displaying a high-affinity binding site for bilirubin. It is competitively inhibited by grape anthocyanins, including aglycones and their mono- and di-glycosylated derivatives. In plant cells, anthocyanins are synthesized in the cytoplasm and then translocated into the central vacuole, by mechanisms yet to be fully characterized. The aim of this work was to determine whether a homologue of rat liver bilitranslocase is expressed in carnation petals, where it might play a role in the membrane transport of anthocyanins. The bromosulfophthalein-based assay of rat liver bilitranslocase transport activity was implemented in subcellular membrane fractions, leading to the identification of a bromosulfophthalein carrier (KM = 5.3 μM), which is competitively inhibited by cyanidine 3-glucoside (Ki = 51.6 μM) and mainly noncompetitively by cyanidin (Ki = 88.3 μM). Two antisequence antibodies against bilitranslocase inhibited this carrier. In analogy to liver bilitranslocase, one antibody identified a bilirubin-binding site (Kd = 1.7 nM) in the carnation carrier. The other antibody identified a high-affinity binding site for cyanidine 3-glucoside (Kd = 1.7 μM) on the carnation carrier only, and a high-affinity bilirubin-binding site (Kd = 0.33 nM) on the liver carrier only. Immunoblots showed a putative homologue of rat liver bilitranslocase in both plasma membrane and tonoplast fractions, isolated from carnation petals. Furthermore, only epidermal cells were immunolabelled in petal sections examined by microscopy. In conclusion, carnation petals express a homologue of rat liver bilitranslocase, with a putative function in the membrane transport of secondary metabolites. © 2005 FEBS
Characterization of electrogenic bromosulfophthalein transport in carnation petal microsomes and its inhibition by antibodies against bilitranslocase
No full textUptake of bilirubin into HepG2 cells assayed by thermal lens spectroscopy. Function of bilitranslocase
No full textProperties of flavonoids influencing the binding to bilitranslocase investigated by neural network modelling
No full textBilitranslocase is a plasma membrane carrier firstly identified on the sinusoidal (vascular) domain of liver cells and later on also in the gastric epithelium. It transports diverse organic anions, such as bilirubin, some phthaleins and many dietary anthocyanins, suggesting that it could play a role both in the absorption of flavonoids from dietary sources and in their hepatic metabolism. This work was aimed at characterising the interaction of bilitranslocase with flavonols, a flavonoid sub-class. The results obtained show that, contrary to anthocyanins, flavonol glycosides do not interact with the carrier, whereas just some of the corresponding aglycones act as relatively poor ligands to bilitranslocase. These data point to a clear-cut discrimination between anthocyanins and flavonols occurring at the level of the bilitranslocase transport site. A quantitative structure-activity relationship based on counter propagation artificial neural network modelling was undertaken in order to shed light on the nature of flavonoid interaction with bilitranslocase. It was found that binding relies on the ability to establish hydrogen bonds, ruling out the involvement of charge interactions. This requisite might be at the basis of the discrimination between anthocyanins and flavonols by bilitranslocase and could lie behind some aspects of the distinct pharmacokinetic properties of anthocyanins and flavonols in mammals
- …
