effect of g protein lipid modifications on g protein membrane interactions

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  • S26 Abstracts / Chemistry and Physics of Lipids 149S (2007) S23S49

    the membrane lipid composition, it must be connectedto the remainder of the protein via a flexible molec-ular hinge that allows transmembrane domain VII toreside in the membrane in the normal mode and exitto the peripmode. Theextra-memmembranetopology isthe transloproteinlipogy is neceof lipids onproper topolipids withlipids, regasupport up



    PO 7Effect ofprotein mPablo V. ELlado, Silv

    MolecularBiomedicinBalearic Is

    G proteinsreceptors (agonist binup to threepalmitate aG proteinthe numbemembraneregulate thin turn regteins, we hproteinmetified thelamellar anabsence ofFor this pu(G), dimmembraneconcentratithe aboveby centrif

    immunoblotting. We have observed that these lipidsinduced relevant changes in the structural properties ofmembranes and in the interaction of G proteins to mem-branes. The main effects were induced by isoprenyl

    ties (gh incctionof PE aneasesand tctivelitic acubunit




    oxidamila Fshcha

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    y memstresscompxidanhenyle ba

    ichfd fattyity and. Oure rang

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    -anglePR-spthermfferend out tn homtural sroteinnels alasmic side of the membrane in the invertedrefore, the net charge of the cytoplasmicbrane surface and the charge character of thelipid headgroups determine topology. Finalestablished after the N-terminal bundle exits

    con and is therefore primarily determined byid interactions. Although near normal topol-ssary for uphill transport activity, the effectstopology and function are not coupled. Whilelogy requires balancing of anionic lipids bynet zero charge, only non-bilayer-forming

    rdless of their different chemical character,hill transport activity.ledgement: Supported by NIH grant


    G protein lipid modications on Gembrane interactions

    scriba, Jesus Casas, Rafael Alvarez, Victoriaia Teres

    Celle/Biology-IUNICS/University of thelands, Spain

    are in molar excess over G protein-coupledGPCR) to enable signal amplification uponding. Each G protein heterotrimer can bearsimultaneous lipid modifications (myristate,nd isoprenyl residues), which contribute tomembrane interactions. In GPCR clusters,r of G protein lipids inserted in the plasmacould be very high. Because these lipids cane physical properties of membranes, whichulate the interaction and activity of G pro-ave studied the effect of these lipids on Gmbrane interactions. Thus, we have quan-

    binding of G proteins to membranes withd nonlamellar propensity in the presence ormyristate, palmitate or isoprenyl moieties.

    rpose, we used purified G protein monomersers (G) and trimers (G) and models (liposomes) formed with PC and variousons of PE in the absence or presence oflipids. G protein binding was determined

    ugation analysis, followed by quantitative

    moiewhic(redutureof G(incrmers

    respepalmG sand G


    PO 8ChaandmemantiLiudGolo1 EmAcadof CeMantivelipidantiooxypas thAOsurateactivtivelya widfuncEhrliwere

    rightby ETheby difoundatiostructal pchaneranyl-geraniol), present in the G protein,reased nonlamellar (HII) phase propensityin 12 C in the L-to-HII transition tempera-), concomitant with increases in the bindingd G to nonlamellar-prone membranes

    of about 60 and 120% in the binding of dim-rimers to PC:PE 6:4, mol:mol, membranes,y). These results suggest that myristic andid are not as relevant as isoprenyl moieties ofs in the regulation of the membrane structureein interaction with membranes.


    in structural state of the lipid phasekeletal proteins of cellulares under the action of hybridntsatkullina 1, Olga Vekshina 1, Alexanderpov 1, Elena Burlakova 1, Yuri Kim 2

    Institute of Biochemical Physics, Russianf Sciences, Russia; 2 Institute of Biophysicsssian Academy of Sciences, Russiabrane pathologies are characterized by oxida-and significant changes in structural state,osition and functioning of membranes. Thet (AO) phenozan [-4-oxy(3,5-ditertbutyl-4-)potassium propionate] was used at IBCPsic compound in the synthesis of hybridans by addition of choline residue and sat-acid tail to enhance the anticholinesteraseto increase the rigidity of membranes respec-main aim was to study the effect of AO ine of concentrations on certain structural and

    parameters of membranes of erythrocytes anditic carcinoma cells in vitro. The ionic flowsured potentiometrically with recording oflight scattering; the viscosity of membranes,ectroscopy using paramagnetic spin probes.ograms of erythrocyte shades were analyzedtial adiabatic scanning microcalorimetry. Wehat the changes in the system of lipid peroxi-eostasis in membranes result in changes of thetate of lipids (microviscosity) and cytoskele-s, followed by functional shifts of Ca2+K+nd changes of cell reactions. These results


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