trans-bilayer orientation and voltage-dependence of alpha-latrotoxin-induced channels

• Published in: Proceedings of the Royal Society of London. Series B, Biological sciences Biological sciences, 1984-02, Vol.220 (1221), p.477-487
• Main Authors: Robello, M., Rolandi, R., Alemá, S., Grasso, A.
• Format: Article
• Language: English
• Subjects: animal health; animal parasites and pests; animal physiology; Artificial membranes and reconstituted systems; Bathing; Biological and medical sciences; Cell membranes; Electric current; Electric potential; Fundamental and applied biological sciences. Psychology; Lipid bilayers; Lipids; Membrane physicochemistry; Molecular biophysics; Neurons; Spiders; Steady state current; Toxins
• ISSN: 0080-4649; 0962-8452; 2053-9193; 1471-2954
• DOI: 10.1098/rspb.1984.0014

α-Latrotoxin, a polypeptide and potent presynaptic neurotoxin, interacts with artificial lipid bilayers inducing a large increase of conductance, when added to one (cis side) of the two bathing solutions. These conductance changes are due to the presence of channels which, in 0.1 m monovalent cation solution, have conductances between 100 and 400 pS. Current-voltage relations of macroscopic and single channel conductances show marked non-ohmic behaviour being reduced at positive potentials, referred to cis side as virtual ground. The decrease in conductance at high positive voltage is modulated by lipid composition and abolished by digestion with pronase of a trans-bilayer protruding domain of the protein. The results are consistent with the notion that α-latrotoxin forms channels and provide evidence that the molecule is endowed with a specific mode of insertion and orientation in lipid bilayers.