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  • The equinatoxin N-terminus is transferred across planar lipid membranes and helps to stabilize the transmembrane pore
    Kristan, Katarina ...
    Equinatoxin II is a cytolytic protein isolated from the sea anemone Actinia equina. It is a member of the actinoporins, a family of eukaryotic poreformingtoxins with a unique mechanism of pore ... formation. Equinatoxin II isa 20 kDa cysteineless protein, with sphingomyelin-dependent activity. Recentstudies showed that the N-terminal region of the molecule requires conformational flexibility during pore formation. An understanding of the N-terminal position in the final pore and its role in membrane insertion and pore stability is essential to define the precise molecular mechanism of pore formation. The formation of pores and their electrophysiologic characteristicswere studied with planar lipid membranes. We show that amino acids at positions 1 and 3 of equinatoxin II are exposed to the lumen of the pore. Moreover, sulfhydryl reagents and a hexa-histidine tag attached to the N-terminus revealed that the N-terminus of the toxin extends through the pore to the other (traps) side of the membrane and that negatively charged residuesinside the pore are crucial to define the electrophysiologic characteristics of the channel. Finally, we detected a new, less stable, statewith a lower conductance by using a deletion mutant in which the first five N-terminal amino acids were removed. We propose that the first five aminoacids help to anchor the amphipathic helix on the traps side of the membrane and consequently stabilize the final transmembrane pore.
    Vir: FEBS journal. - ISSN 1742-464X (Letn. 274, 2007, str. 539-550)
    Vrsta gradiva - članek, sestavni del
    Leto - 2007
    Jezik - angleški
    COBISS.SI-ID - 22427353

vir: FEBS journal. - ISSN 1742-464X (Letn. 274, 2007, str. 539-550)
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