Dependence of the conductance of the alpha-latrotoxin channel on applied potential and potassium concentration.
alpha-Latrotoxin, with a molecular weight 130,000, is the main component of black widow spider venom, and acts at the presynaptical level, inducing a notable release of neurotransmitters in the synapses of all vertebrates. In artificial lipid membranes, this neurotoxin induces the formation of cation-selective ionic channels, whose conductance depends on the intensity and direction of the applied potential. In fact, also in the presence of symmetrical solutions of potassium chloride, the voltage-current characteristics of the single channel strongly rectify. Such rectification, which depends on the concentration of the ions in solution, can be described by a one-site, one-ion model for a channel. The data fit provides the values of the three parameters describing the model. Moreover, a statistical analysis of the amplitude of the single channel, as a function of the concentration of potassium chloride, has made it possible to verify the consistency of the model used.
Robello
M
M
Physics Department, University of Genoa, Italy.
D000200:Action Potentials / Q000187:drug effects; D000465:Algorithms; D000818:Animals; D001180:Arthropod Venoms / Q000494:pharmacology*; D004553:Electric Conductivity; D007473:Ion Channels / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism; D008567:Membranes, Artificial; D008970:Molecular Weight; D011188:Potassium / Q000494:pharmacology*; D013111:Spider Venoms / Q000378:metabolism / Q000494:pharmacology*; D013112:Spiders
D001180:Arthropod Venoms; D007473:Ion Channels; D008563:Membrane Lipids; D008567:Membranes, Artificial; D013111:Spider Venoms; C020763:alpha-latrotoxin; D011188:Potassium