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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Functional interactions of 14-3-3 proteins with phospholipase D and the M3 muscarinic receptor

Collins, D. M. 2005 (has links)
14-3-3 proteins are a family of small, acidic, scaffolding and adaptor proteins, which have been implicated in cell cycle regulation, apoptosis and signal transduction mechanisms. There are seven isoforms of 14-3-3 (β, η, γ, ε, τ/θ, σ, and ζ) that form hetero-and homodimers in vivo. Recently, 14-3-3 has been shown to associate with members of the heptahelical, plasma membrane spanning G-protein coupled receptor (GPCR) superfamily. GPCRs mediate neurotransmitter and other extracellular agonist-evoked activation of intracellular effectors and signalling cascades. Some of these effector mechanisms lead to the activation of phospholipase D (PLD). Mammalian PLD isoforms catalyse the hydrolysis of phosphatidylcholine, forming choline and phosphatidic acid, a novel second messenger molecule. 14-3-3 dimers associate with other proteins containing specific target motifs, including an RSxpSxP motif (where pS is phosphoserine), or an unphosphorylated WLDLE/DALDL motif. We recognised that the former motif is present in mammalian PLD1 at residues 712-717 and therefore have investigated whether 14-3-3 isoforms associate with PLD and GPCRs to provide a functional role in intracellular signalling.  It was shown, using in vitro GST-fusion protein pull-downs and co-immunoprecipitation, that in CAS 7 cells, 14-3-3 associates with the M3 muscarinic receptor. 14-3-3 was also demonstrated to associate with PLD1, and to a lesser extend PLD2, in an isoform-dependent manner. The effect of PLD activation by protein kinase C (PKC) on this interaction was investigated using the aforementioned techniques and confocal microscopy. Furthermore, in whole cell signalling assays, the overexpression of different 14-3-3 isoforms selectively modified PKC or GPCR-mediated activation of PLD. In addition, PLD was found to physically associate with the M3 receptor. The implications of these interactions for physiological signalling by the M3 receptor and PLD are discussed.
2

Computational and experimental studies of membrane peptide interactions

Balali-Mood, K. 2005 (has links)
This thesis describes the combination of experimental (E-ray and neutron diffraction) and computational techniques (molecular dynamics simulations) to investigate membrane peptide interactions. Initially, a computational model for a dioleylphosphatidyl choline (DOPC) bilayer was constructed. This bilayer had been verified with experimental data (namely area per headgroup, volume per lipid, order parameter of the oleyl chains and electron density profile). A mixed bilayer of DOPC and diolelylphopshatidyl glycerol (DOPG) was then constructed. The mixer bilayer was verified in the same manner. A peptide (adenosine diphosphate ribosylation factor-1 (pARF-1)) was then inserted into the pre-equilibrated mixed bilayer. The orientation of this peptide with respect to the membrane was based on previous neutron diffraction studies, carried out by other group members. Four possible orientations had resulted from analysis of the neutron data. The four orientations of a pARF-1 were then subjected to molecular dynamics simulations. The time course of these simulations was 4 ns. The simulations’ trajectories were analysed for each of the four models. Particular emphasis was placed upon the positional changes of the phenylalanine label positions that were derived from the neutron data. It was concluded that model A was the most likely orientation of pARF-1 in relation to the bilayer. Having established the technique, and confirmed that the most likely orientation of the peptide was what was originally proposed, another peptide, the fusion peptide of simian immunodeficiency virus (SIV) was placed into a previously equilibrated DOPC bilayer. In this case, only the proposed orientation of the SIV fusion peptide in relation to the bilayer was studied utilizing molecular dynamics simulations. The results are interpreted in relation to the actions of SIV fusion peptide upon the membrane, with particular emphasis on the disruption of oleyl chain order parameters.
3

Motor cooperation in bi-directional early endosome motility

Schuster, Martin 2011 (has links)
In mammalian cells and fungi, early endosomes form a dynamic compartment that undergoes bi-directional motility along microtubules. Previous work has shown that in the model system Ustilago maydis early endosome motility involves the opposing motor proteins dynein and kinesin-3. Here I performed a detailed analysis of the role of the motors in early endosome motility, using quantitative live cell imaging of kinesin-3, dynein and the endosomal GTPase Rab5a. In the first part of my work, I analysed the role of dynein at MT plus-ends, where the motor forms a strong accumulation that was thought to be involved in capturing early endosomes. I could demonstrate that ~55 dynein motors build up the dynein accumulation. In collaboration with Ms. Congping Lin and Prof. Peter Ashwin (Institute for Mathematics, Exeter), I found theoretical evidence that ~25 dynein motors concentrate and leave the plus-ends stochastically. In addition, dynein motors are captured by an interaction of dynactin and the plus-end binding protein EB1. Together both mechanisms increase the number of motors, which ensures that EEs will be loaded onto dynein before they reach the end of their track. In a second project, I provide evidence that loading of dynein is not restricted to the plus-ends. Instead, dynein leaves the plus-ends and is able to bind to kinesin-3 delivered early endosomes, which changes their transport direction from anterograde to retrograde. Kinesin-3 remains bound to these retrograde EEs. When dynein leaves the organelle, it switches back to anterograde motility. Interestingly, a single dynein wins over three to five kinesin-3 motors. I discuss these findings in the light of current motor cooperation concepts. In a third part, I demonstrated that kinesin-3 has an unexpected role in long-range retrograde endosome motility. In contrast, dynein is only responsible for the distal 10-20 µm. This is possible because most of the hyphal cells contain a symmetric and bi-polar MT array. This MT organization is reminiscent of that in dendrites. Kinesin-3-based retrograde motility is required to mix the organelles and might support long-range communication between both cell poles.
4

Membrane fusion induced by poly (ethylene glycol)s and by retinol and its derivatives

Goodall, A. H. 1978 (has links)
No description available.
5

Synthesis of ligands for the large conductance calcium activated potassium channel (BK←c←a)

Power, Eoin Christopher 2001 (has links)
No description available.
6

Studies on Ribosome-Membrane Interactions

Cooper, M. B. 1977 (has links)
No description available.
7

Identification of amino acid residues of the NR2A subunit that control glutamate potency in recombinant NR1/NR2A NMDA receptors

Chen, Philip Eng-Chi 2000 (has links)
No description available.
8

Studies on Calcium Uptake by Mouse Fibroblasts and its Relation to Cell Proliferation

Damluji, R. K. 1978 (has links)
No description available.
9

The role of 5-HT←1←a receptors in the control of cardiorespiratory reflexes

Skinner, Matthew Richard Alistair 1999 (has links)
No description available.
10

Studies on the Interactions of Reticular Membranes with Ribosomes

Dani, H. M. 1977 (has links)
No description available.

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