Dissertations / Theses on the topic 'Membranes plasmiques'
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Gilson, Virginie. "Interaction du peptide beta amyloïde avec les membranes plasmiques cellulaires." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAJ020/document.
Full textAlzheimer’s disease (AD) is a neurodegenerative disease of the central nervous system which is characterized in particular by the accumulation of beta amyloïde peptide (Aβ) in nerve tissues. In the first part of this thesis we showed that the interaction of high molecular weight Aβ1-42 oligomers with the plasma membrane of differenciated PC12 or nerve cells (neurons and astrocytes) triggers variations of their depending on the activation of the NMDA receptors. In the second part we showed that a pre-exposure of PC12 and nerve cells with low concentrations Aβ1-42 of modulates the later interaction of oligomers with the plasma membrane. Finally in collaboration with the company Innovative Health Diagnostics (IHD) we participated in the characterization of a fluorescent amyloid probe developed to realize detection test of AD from blood samples
Morand, Olivier. "Mécanismes de transport des acides gras au travers des membranes plasmiques." Paris 7, 1985. http://www.theses.fr/1985PA077070.
Full textKhalfoun, Bachir. "Etude biochimique et immunologique des membranes plasmiques syncytiotrophoblastiques isolées du placenta humain à terme." Tours, 1985. http://www.theses.fr/1985TOUR3807.
Full textNDUWIMANA, JEAN. "Etude d'une serine protease de membranes plasmiques de foie de rat : approche biochimique et moleculaire." Rennes 1, 1993. http://www.theses.fr/1993REN10170.
Full textSarrouilhe, Denis. "Etude de l'activite proteine phosphatase endogene de la phosphatase alcaline des membranes plasmiques de foie de rat." Poitiers, 1992. http://www.theses.fr/1992POIT2289.
Full textThibault, Gilles. "Effet inhibiteur de membranes plasmiques syncytiotrophoblastiques du placenta humain à terme sur l'activation lymphocytaire : approche du mécanisme d'action." Tours, 1991. http://www.theses.fr/1991TOUR3804.
Full textGUEBLE-VAL, FLORENCE. "Etude des activites proteolytiques des membranes plasmiques dans le foie normal et dans l'hepatome experimental chez le rat." Rennes 1, 1988. http://www.theses.fr/1988REN10039.
Full textHeyno, Eiri. "Enzymes impliqués dans la production des formes réactives de l'oxygène dans les membranes plasmiques, les mitochrondries et les chloroplastes." Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00447102.
Full textManenti, Stéphane. "Organisation moleculaire de la mp26 dans les membranes plasmiques des fibres du cristallin et dans un systeme reconstitue (proteoliposomes)." Paris 6, 1988. http://www.theses.fr/1988PA066387.
Full textManenti, Stéphane. "Organisation moléculaire de la MP26 dans les membranes plasmiques des fibres du cristallin et dans un système reconstitué (protéoliposomes)." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37615673n.
Full textLatoud, Chantal. "Etude des interactions d'antifongiques peptidolipidiques, iturine A et bacillomycine L, avec les membranes plasmiques d'érythrocytes et de cellules de levure." Lyon 1, 1988. http://www.theses.fr/1988LYO10082.
Full textPayrastre, Bernard. "Etude du métabolisme des phosphoinositides dans les membranes plasmiques des cellules A431 : effet du facteur de croissance de l'épiderme (EGF)." Toulouse 3, 1989. http://www.theses.fr/1989TOU30168.
Full textDupou, Laurence. "Contribution a l'etude de la dynamique et de la distribution laterale des lipides dans les membranes plasmiques de cellules eucaryotes." Toulouse 3, 1987. http://www.theses.fr/1987TOU30043.
Full textDupou, Laurence. "Contribution à l'étude de la dynamique et de la distribution latérale des lipides dans les membranes plasmiques de cellules eucaryotes." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37604764h.
Full textLatoud, Chantal. "Etude des interactions d'antifongiques peptidolipidiques, iturine A et bacillomycine L, avec les membranes plasmiques d'érythrocytes et de cellules de levure." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376150401.
Full textCazeils, Jean-Luc. "Caractérisation de la composition lipidique des membranes plasmiques des hépatocytes de foies d'oies : relation avec le rendement technologique des foies gras." Toulouse, INPT, 2000. http://www.theses.fr/2000INPT001A.
Full textCluchague, Nicolas. "Vers la caractérisation de l'organisation des membranes plasmiques de muscles déficients en dystrophine : étude sur la souris mdx et le chien grmd." Rennes 1, 2004. http://www.theses.fr/2004REN1B082.
Full textMolee, Wittawat. "Facteurs de variation de la composition lipidique des membranes plasmiques des hepatocytes chez les palmipedes : relation avec le rendement technologique des foies gras." Toulouse, INPT, 2006. http://ethesis.inp-toulouse.fr/archive/00000252/.
Full textMolee, Wittawat Babilé René. "Facteurs de variation de la composition lipidique des membranes plasmiques des hepatocytes chez les palmipedes relation avec le rendement technologique des foies gras /." Toulouse : INP Toulouse, 2006. http://ethesis.inp-toulouse.fr/archive/00000252.
Full textMalgat, Monique. "Biosynthèse de sphingomyélines à cholines et à éthanolamine dans les microsomes et les membranes plasmiques de foie et de cerveau de rat : localisation de l'enzyme microsomal." Bordeaux 2, 1986. http://www.theses.fr/1986BOR22025.
Full textMoreau, Céline. "Organisation des phospholipides des membranes plasmiques de muscle squelettique : etude par spectroscopie de rmn du phosphore*31 et microscopie electronique (doctorat : genie biologique et medical)." Rennes 1, 2000. http://www.theses.fr/2000REN1B049.
Full textMalgat, Monique. "Biosynthèse de sphingomyélines à choline et à éthanolamine dans les microcosmes et les membranes plasmiques de foie et de cerveau de rat localisation de l'enzyme microsomal." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37599399z.
Full textANGULO, GUERRERO JESUS OFELIA. "Effets de differentes deficiences nutritionnelles en agpi sur la composition lipidique et la physiologie des membranes mitochondriales et plasmiques des cellules hepatiques et cerebrales chez le rat." Paris 11, 1991. http://www.theses.fr/1991PA112225.
Full textAndré, Aurore. "Etude de l'influence de l'environnement lipidique sur la fonctionnalité et l'organisation membranaire des récepteurs mu et delta aux opioïdes." Toulouse 3, 2009. http://thesesups.ups-tlse.fr/542/.
Full textNumerous evidences show the existence of lateral heterogeneities within the plasma membranes defined as lipid domains. Among these, lipid rafts, have been extensively studied. They are characterised by an enrichment in cholesterol and sphingolipids, and are depicted as fluid plaforms that segregate membrane components involved in a particular signaling process, like signal transduction of GPCR, promoting the specificity and the efficiency of the response. Here we study the role of the lipidic environment on the activity of two GPCRs, namely human mu and delta opioid receptors (hMOR and hDOR). Cholesterol, which is a main component implicated in the formation of rafts, was here the subject of a particular interest. Membranes fractions that were enriched in cholesterol (DRM) were analysed after cold extraction by TX-100 of cellular membranes. The data we obtained show that hMOR and hDOR are found in DRM at a basal state. In contrast, when activated by an agonist, a relocalisation of a fraction of these receptors is observed in DRM and we show that this phenomenon is dependant of the association of these receptors with G-proteins. The analysis of pharmacological properties of hDOR and hMOR upon cholesterol depletion show clearly that some pool of receptors need cholesterol for function. To complete these data, we next examined whether this effect was due to direct interactions of the receptors with cholesterol or membrane thickness. To test this assumption, we have investigate the effect of ergosterol on hMOR and hDOR pharmacology and the acyl-chain length of the phospholipids on the function of the reconstituted hDOR
Conchonaud, Fabien. "Dynamique de l'organisation de la membrane plasmique et incidence fonctionnelle." Aix-Marseille 2, 2008. http://www.theses.fr/2008AIX22026.
Full textThe extraordinary coherence of the plasma membrane results from molecular interactions of weak energy between the membrane components. In fact, the molecules organize and segregate according to their respective affinities, creating local heterogeneities within the plasma membrane. Regarding this organisation, fundamental questions are to understand on which spatio-temporal scales these heterogeneities take place and to identify to what extent such dynamic organization contributes to control basic cellular functions. In order to answer these questions, it was necessary in the first time to establish and validate a robust experimental approach making possible the identification and description of the plasma membrane heterogeneities. A systematic use of the FCS performed at variable wait of observation has made possible to establish the fundamental implication of certain classes of lipids in the generation of these heterogeneities. The second focus of this study was primarily devoted to explore the impact of such membrane organization on various fundamental cellular functions. Thus, molecular partitioning has an important effect signal delivery by modulating the intensity of the outcome signal. In other terms, if the molecules preserve their capacity to signal, it clearly appears that this dynamic micro-organization of the membrane controls the amplitude of the signal. In conclusion, our results have allowed us to clarify debated points but also to raise several news questions which will the subject of future studies like the coupling between the two membrane leaflets, the impact of the membrane component exchanges/cytoplasm or membrane recycling on the regulation of cellular functions
Botcazon, Camille. "Etude du mode d'action de composés antifongiques membranotropes naturels sur deux Sclerotiniacées : cas des rhamnolipides et des fengycines." Electronic Thesis or Diss., Compiègne, 2023. https://bibliotheque.utc.fr/Default/doc/SYRACUSE/2023COMP2755.
Full textRhamnolipids (RLs) and fengycins (FGs), are compounds produced by bacteria displaying antifungal properties against the phytopathogenic fungi Sclerotinia sclerotiorum and Botrytis cinerea. However, the induced biocidal effects, and the involved mechanisms are poorly understood in fungi. Due to their amphiphilic properties, a membranotropic mode of action is proposed for these interesting compounds for biocontrol. The present work demonstrates that the two Sclerotiniaceae have opposite sensitivities to RLs and FGs. A microscopy study shows that RLs can induce programmed cell death (PCD) or necrotic cell death in both fungi depending on the concentration whereas FGs systematically induce PCD, probably by triggering autophagy. Lipidomic analyses (fatty acid, phospholipid and ergosterol contents) of S. sclerotiorum and B. cinerea strains differently sensitive to RLs and FGs allow to correlate the lipid contents of the fungi to their sensitivities. These data are used to study the interactions of RLs or FGs on biomimetic plasma membrane models of the two fungi. The dynamics show that the RLs monomers insert into the models without fluidizing them and that the FGs auto-aggregate themselves and insert into some models, inducing fluidization. Ergosterol and phosphatidic acids seems to disfavour this insertion while phosphatidylcholine and phosphatidylethanolamine seem to favour it.This work allows to better understand the antifungal mode of action of RLs and FGs, with a view to develop more effective biocontrol products for crop protection targeting specific pathogens
BERGER, GAETAN. "La membrane des granules alpha : miroir de la membrane plasmique plaquettaire." Paris 7, 1995. http://www.theses.fr/1995PA077163.
Full textMénorval, Marie-Amélie de. "Etude de la perméabilisation de la membrane plasmique et des membranes des organites cellulaires par des agents chimiques et physiques." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA114840/document.
Full textIt is possible to permeabilize the cellular plasma membrane by using chemical agents (as polyethylen glycols or diméthylsulfoxyde) or physical agents (as ulstrasounds or electric pulses). This permeabilization can be reversible or not, meaning that after the permeabilization, the membrane recovers its integrity and its hemi-permeable properties. These techniques can be used for the uptake of medicines or nucleic acids or to generate cellular fusions. A recent approach, the molecular dynamics, uses numerical simulations to predict the effects of permeabilizing agents at the molecular scale, allowed generating of new data to understand the molecular mechanisms that are not completely known yet.The pulses so called “classical” in electropermeabilization, from the range of the ten of milliseconds to the hundred of microseconds and with a field amplitude in the range of 100 kV/m, can only permeabilize the plasma membrane. However, more recently, shorter pulses, so called nanopulses (few nanosecondes) and with an higher field amplitude (in the range of 10 MV/m) have been used and allow to affect also cellular organelles membranes.This thesis is, in a first time, about the permeabilizing effects of a chemical gent (the diméthylsulfoxyde, DMSO) by comparing predictive models from molecular dynamics with experiments in vitro on cells. The numerical model predicts three regimes of action depending on the DMSO concentration. Used at low concentration, there is a plasma membrane deformation. The use of an intermediate concentration lead to membrane pores formation and higher DMSO concentrations resulted in membrane destruction. The experiments done in vitro on cells confirmed these results using the following of permeabilization markers. This study has been compared to permeabilization due to a physical agent (electric pulses).Secondly, it is about the development and the use of a new cell exposure device for nanopulses that permit to apply very high electric fields and to observe induced cellular effects simultaneously by microscopy.To finish, this device has been used with nanopulses to generate calcium peaks in mesenchymal stem cells that are presenting spontaneous calcium oscillations in correlation to their differentiation state.. These induced peaks are due to the release of the calcium stored in organelles and/or to plasma membrane permeabilization leading to a intramembrane calcium flux establishment. It is also possible to use microsecond pulses to generate calcium peaks in these cells. In this case, the calcium peaks are due to the plasma membrane permeabilization . By changing the amplitude of the applied electric fields and the presence or the absence of external calcium, it is possible to manipulate cytosolic calcium concentrations by mobilizing internal or external calcium. One feature of these new tools is to be triggered and stopped instantly without reminiscence, unlike chemical molecules permitting the production of calcium peaks. These tools could therefore lead to a better understanding of the involvement of calcium in mechanisms such as differentiation, migration or fertilization
Carvalho, Kévin. "Interaction entre membrane plasmique et cytosquelette : approche biomimétique pour l’étude des interactions entre ezrine, PIP2 et actine." Montpellier 2, 2009. http://www.theses.fr/2009MON20175.
Full textThe plasma membrane is composed of several different lipids and can interact directly with the actin cytoskeleton via specific lipids and linker proteins. Among these is the ERM (Ezrin, Radixin, Moesin) family of proteins, which is involved in the direct linkage of the membrane to the actin cytoskeleton via a phosphatidylinositol (4,5) biphosphate (PiP2) lipid binding site. Our aim is to understand the interactions between these proteins and PiP2 using in vitro simplifed biomimetic systems like giant unilamellar vesicles (GUV) containing PiP2. We showed that a conformational change of ezrin occur when the protein binds to PiP2, this conformational change allowing ezrin to bind to actin filaments. We have characterized quantitatively the incorporation of PIP2 in the membrane of giant vesicles, and showed that the interaction of ezrin with GUV induce a partitioning of the lipid within the membrane as well as ezrin aggregates on the membrane. Likewise, ezrin oligomers were observed only in the presence of PiP2. A better understanding of the interplay between ezrin, PIP2-containing membranes and actin will help to get a better view of the role of ezrin in cellulo
Pavoine, Catherine. "La pompe à calcium de la membrane plasmique de l'hépatocyte." Paris 6, 1986. http://www.theses.fr/1986PA066424.
Full textPavoine, Catherine. "La Pompe à calcium de la membrane plasmique de l'hépatocyte." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb376002974.
Full textAubry, Jacques. "Etude fonctionnelle et enzymatique de la membrane plasmique de plasmocytome murin." Nantes, 1989. http://www.theses.fr/1989NANT01VS.
Full textPari, François Michel. "Etude d'une proteine de la membrane plasmique de l'oligodendrocyte en culture." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13098.
Full textPari, François Michel. "Etude d'une protéine de la membrane plasmique de l'oligodendrocyte en culture." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376172793.
Full textBiniek, Catherine. "Importance des ROS et des radicaux : de la graine à la membrane plasmique." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS483/document.
Full textThe aim of this work is to define the effects of adverse environmental conditions on seed quality of A.thaliana, H.annuus, B.oleracea et H.vulgare), characterize two A.thaliana mutants affected in plasma membrane proteins and characterize the activity of the two proteins. Seeds were harvested from plants subjected to drought and/or thermal stress. Then O₂•⁻ and organic radicals in seeds were measured showing no impact of the stress. Accelerated ageing had a negative effect on seed vigor and viability. Radicals have been identified by high field EPR: epi-catechin and Mn(II) in the testa and melanin in the pericarp. There was no correlation between these radicals and the seed quality, therefore these radicals were not found to be good markers of seed quality. A.thaliana KO mutants of quinone reductase (QR) and AIR12 have been characterized. QR are cytosolic enzymes that have an affinity for the membrane. QR catalyze the reduction of quinone to dihydroquinone. Thus they are known to be protective enzymes against oxidative stress. However, at alkaline pH, dihydroquinone deprotonize and form semiquinones and O₂•⁻. AIR12 is a b561 cytochrome anchored to the apoplastic side of the membrane. These proteins could be implied in a transmembrane electron transport via vitamin K1. Recombinant proteins and NQR and AIR12 were produced. At alkaline pH, AIR 12 was reduced by the semiquinone, AIR12 could form a redox couple with vitamin K1 as electron shuttle across the membrane. In the presence of plasma membrane, the production O₂•⁻ was increased with NQR and reduced with NQR and AIR12. QR appear to have an anti- and pro-oxidant according to the conditions and AIR12 an anti-oxidant role. Electron transfer between the two proteins could be done via the semiquinone at alkaline pH and via O₂•⁻
Kreder, Rémy. "Sondes moléculaires multifonctionnelles pour l'imagerie de fluorecence de membranes cellulaires." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAJ006/document.
Full textBased on rational molecular design, we design new membrane probes that enable fluorescence imaging of cell plasma membrane organization. In this work, we first synthesized a toolkit, based on solvatochromic Nile Red dye and Black Hole Quencher-2, that can stain specifically ordered and disordered lipid domains (rafts) and identify them by the emission color. Cellular studies with these probes suggested that the plasma membrane is composed of two distinct phases. Then,with the idea to make Nile Red-based probes compatible with serum medium and fixable by formaldehyde/glutaraldehyde, we modified previously developed probe NR12S with PEG and aminogroups, respectively. Surprisingly, the PEGylated probe is quickly internalized inside the cell and the amino-derivative aggregates with the fixing agent. On the other hand, based on Nile Red we designed probes capable to detect a given receptor and visualize its lipid environment. Initially, we obtained probes that can turn-on fluorescence on binding to the oxytocin GPCR receptor. Then, we conjugated NR12S through a PEG(12) spacer to the ligand of intergrin, RGD. The first data show that the molecule can bind to the membrane and detect the lipid order, though cellular studies have to be completed. We also worked on fluorogenic (turn-on) membrane probes for multi-color imaging. Based on blue 3-methoxychromone dyes, we obtained probes that are brighter and more photostable than the originally developed probe based on 3-hydroxychromone (F2N12S). Due to large Stocks shift, they enabled cell membrane imaging with minimal auto-fluorescence in the blue spectral region, compatible with common green and red probes. At the end, based on squaraine fluorophore, we developed three new probes operating in the far red region, which is also very interesting for in vitro and in vivo imaging. These dyes show a parallel orientation with the lipid membrane, while the cellular experiments point out that only the probe with two anchor groups is able to stain stably the plasma membrane. The probes developed here are expected to be used for lipid rafts research as well as for super-resolution and multi-color imaging of living cells
Zarubica, Ana. "Influence du transporteur ABCA1 sur le microenvironnement lipidique de la membrane plasmique." Aix-Marseille 2, 2009. http://theses.univ-amu.fr.lama.univ-amu.fr/2009AIX22025.pdf.
Full textThe ABCA1 transporter is involved in the Apo A-I/mediated removal of cellular phospholipids and cholesterol at the cell membrane. Considering that ABCA1 acts as lipid translocator we investigated the effect of the transporter on membrane lipid microenvironment. By biochemical assays, we demonstrated that the ATP-ase activity of ABCA1 modifies the partitioning in lipid rafts of the transporter itself and other membrane proteins such as the transferrin receptor (TfR), TfR dynamic kinetics and down regulates TfR-mediated endocytosis. We then assessed by biophysical methods, cationic sensors and FLIM, significant modifications of membrane attributes at the inner and outer leaflet in the presence of ABCA1. Furthermore, we evidenced overall changes in membrane dynamics in the presence of ABCA1 by FRAP. Finally, we correlate the mechanistic basis of ABCA1-dependent modulation of macrophage phenotype with the influence of ABCA1 on lipid raft dependent signaling downstream of IFNγR
Bruneau-Wack, Claudine. "Modulation de fonctions cellulaires par des modifications experimentales de la membrane plasmique." Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13059.
Full textMALLAT, ARIANE. "Regulation hormonale de la pompe a calcium de la membrane plasmique de l'hepatocyte." Paris 6, 1989. http://www.theses.fr/1989PA066330.
Full textGRANDMOUGIN, ANNE. "Atpase-h#+ de la membrane plasmique de racines de mais : role des sterols." Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13008.
Full textJullié, Damien. "Les endosomes de recyclage fusionnent transitoirement avec la membrane plasmique des dendrites neuronales." Thesis, Bordeaux 2, 2012. http://www.theses.fr/2012BOR21942/document.
Full textMembrane trafficking is essential for neuronal function: from growth of neurons and synapse formation to recycling of synaptic vesicles and receptors, questions concerning exocytosis and endocytosis are stimulating neurobiology research. In particular, trafficking of glutamate receptors present in recycling endosomes (REs) is necessary for the expression of long term potentiation (LTP). To investigate the mechanism of exocytosis in dendrites, we have imaged cultured rat hippocampal neurons transfected with transferrin receptor, a classical marker of REs, tagged with phluorin. As for AMPA receptors or β2-adrenegric receptors, single exocytic events has revealed two main behaviors: in most cases, receptors diffuse quickly in the plasma membrane after exocytosis (discharge events), but receptors can also remain clustered (display events). Using fast extracellular pH changes around the recorded cell, we show that for display events exocytosis is transient: after a few seconds (median 2.6 s) receptors are internalized. Moreover, using two color imaging of single exocytosis events with markers of neuronal compartments, we found that Rab11 is enriched at the exocytosis site, confirming the endosomal origin of the vesicles. Overexpression of a dominant negative form of Rab11 known to impair LTP decreases selectively the frequency of discharge events. As SNARE proteins are involved in virtually all membrane fusion processes, we investigated the role of Vamp proteins in somatodendritic exocytosis events. We found that Vamp4, unlike Vamp2 or Vamp7, is enriched in TfR containing compartments and can undergo exocytosis at high frequency and is required for TfR exocytosis
Yezid, Hocine. "Mécanismes d'interaction de la protéine Tat du VIH-1 avec les membranes plasmique et endosomale." Montpellier 2, 2009. http://www.theses.fr/2009MON20081.
Full textThe HIV-1 transactivating factor Tat, plays a critical role in HIV-1 pathogenesis. It is strictly required for viral transcription. It can also be secreted by infected cells. Once in the bloodstream, it can enter the cytosol of uninfected cells by endocytosis and dramatically affect their biological activity. Here, we provide evidence that Tat is directly secreted through the plasma membrane using an unconventional secretion pathway. We found that phosphatidylinositol-4,5-bisphosphate, PI(4,5)P2, is responsible for Tat recruitment to the inner leaflet of the plasma membrane, thereby allowing its membrane insertion and translocation. We observed, using a variety of biophysical techniques, that Tat binds specifically and with a very high affinity to a single molecule of PI(4,5)P2. This interaction is mediated by a triplet of basic residues (residues 49-51), and is stabilized by the concomitant membrane insertion of the side chain of Tat-Trp11. This original mechanism restricts Tat binding to membrane embedded PI(4,5)P2, but also enables very tight binding. This high affinity allows Tat to be secreted and to displace cell proteinsƒnƒnfrom the plasma membrane. We also elucidate the molecular mechanism responsible for Tat insertion into the endosome membrane. This insertion is triggered by the low pH (pH ~5. 3) present within the endosome lumen. Acidic pH is detected by a sensor made of Glu2 and an Arg triplet (55-57) that are connected by a salt bridge. Glu2 protonation at low pH will destabilize the salt bridge, thereby allowing Trp11 exposure and enabling membrane penetration. This is the first step of the membrane translocation process that will allow Tat delivery to cytosol
Ludes, Bertrand. ""Approche therapeutique de l'adenocarcinome renal par modification de la structure de la membrane plasmique"." Université Strasbourg I, 1990. http://www.theses.fr/1990STR13185.
Full textGrondin, Alexandre. "Fonction des aquaporines de la membrane plasmique dans les mouvements stomatiques chez Arabidopsis thaliana." Thesis, Montpellier, SupAgro, 2011. http://www.theses.fr/2011NSAM0007.
Full textStomatal movements are mediated by drastic changes in guard cell volume. A role in these processes for water channel proteins named aquaporins has been proposed but not demonstrated. Transcriptome analyses have indicated that several plasma membrane aquaporins (PIPs) including AtPIP1;2 and AtPIP2;1 are expressed in Arabidopsis thaliana guard cells. In the present work, we investigated the function of these two aquaporins in stomatal movements. The stomata of pip1;2 and pip2;1 knock-out mutants showed a normal opening response to light and low CO2, a normal closing response to darkness and high CO2, but were almost insensitive to abscisic acid (ABA)-induced stomatal closure. A direct role of AtPIP1;2 and AtPIP2;1 in water transport was investigated by measurement of guard cell protoplast water permeability (Pf) under darkness, light and light with ABA. The Pf of pip2;1 guard cell protoplasts was significantly reduced, specifically in the presence of ABA. As extracellular hydrogen peroxyde (H2O2) production is essential for intracellular ABA signalling, we also investigated the possibility that AtPIP1;2 and AtPIP2;1 facilitate the diffusion of H2O2 through the guard cell plasma membrane. Time-dependent accumulation of reactive oxygen species in response to ABA was abolished in pip2;1 but not pip1;2 guard cells. In another type of approach, the regulation of the two aquaporins was investigated after production in the yeast Pichia pastoris and functional reconstitution in proteoliposomes. Structure-function analysis was achieved in the case of AtPIP2;1, showing that cytoplasmic residue His199 is involved in both divalent-cation- and proton-mediated gating. In contrast, mutation of Arg124 rendered AtPIP2;1 largely insensitive to calcium while remaining fully sensitive to protons. Over-expression of deregulated forms of AtPIP1;2 and AtPIP2;1 in pip1;2 and pip2;1, respectively, indicated that the gating regulation of these proteins may play an important role in their guard cells functions. Altogether, our results suggest that AtPIP2;1, and to a lesser extent AtPIP1;2, play important and distinct roles in water and H2O2 fluxes during ABA-induced stomatal closure in Arabidopsis thaliana
Fierro-Pastrana, Reyna-Carmen. "Etude de l'architecture moléculaire de la membrane plasmique et des membranes acrosomiques du spermatozoïde humain : leurs modifications au cours des phénomènes de capacitation et de la réaction acrosomique." Nancy 1, 1997. https://hal.univ-lorraine.fr/tel-01747360.
Full textLemaire, Laurine. "Étude des propriétés physico-chimiques de la membrane plasmique comme facteurs modulant l'interaction de molécules et des structures protéiques exogènes." Electronic Thesis or Diss., Compiègne, 2022. http://www.theses.fr/2022COMP2713.
Full textThe plasma membrane was often described as a structure delimiting and protecting the cell from its external environment. However, his role is much more complex and multifunctional. The membrane is an exchange platform at the cellular external and internal environments. Many cellular functions are closely related to it, such as migration, transport of molecules, some pathways of metabolic signaling, or the contact with micro-organisms. This thesis focuses on the study of some cellular processes occurring at the membrane interface using a system that can mimic the lipid bilayer properties. This membrane models that allow a precise control of the in vitro conditions, represent a good alternative to the often inconclusive studies on whole cells. Liposomes allow focusing on a particular function or constituent. In this thesis, the use of the biomimetic model was declined for the study of several processes. The mechanisms of adhesion of flagellated bacteria to lipid bilayers were studied as a function of the physical properties of the lipid bilayers. This information is of paramount importance in the context of antibiotic resistance, giving more information for the potential development of alternative therapies. The liposome model was also used for forming proteoliposomes to study of a transmembrane protein, MRP4 (multidrug resistance associated protein). The study of this protein is an issue in multi-drug treatments. Indeed, this protein is widely involved in drug interactions. Finally, the liposome model was used to characterize the interaction with lipid bilayers of molecules with high therapeutic potential: polyphenols. All of this work was done in collaboration with the team of the Prof Patrick Trouillas (INSERM U1248 team, Limoges University Hospital) working on the development of biomimetic cell models in silico
Ageorges, Agnès. "Analyse comparative des électrophorégrammes bidimensionnels pour la recherche des polypeptides de la membrane plasmique de racines de mai͏̈s impliqués dans le transport de nitrate." Montpellier 2, 1992. http://www.theses.fr/1992MON20091.
Full textSENECHAL, HELENE. "Role des glycoproteines de la membrane plasmique au cours de la differenciation terminale des myoblastes." Paris 7, 1989. http://www.theses.fr/1989PA077114.
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