alpha-latrotoxin forms calcium-permeable membrane pores via interactions with latrophilin or neurexin.
In order to explore the mechanisms by which alpha-latrotoxin activates neurotransmitter release, we have characterized its effects by patch-clamp methods on cells heterologously expressing its receptors, latrophilin-1 or neurexin-Ialpha. Application of alpha-latrotoxin (1 nM) to cells expressing rat latrophilin or neurexin, but not mock-transfected cells, induced a cationic conductance. In cells expressing latrophilin, current development was slow in the absence of divalent cations, but was accelerated by Ca2+ or Mg2+. In cells expressing neurexin, alpha-latrotoxin did not elicit currents in the absence of Ca2+. The toxin-induced conductance was rectifying, persistent, permeable to monovalent and divalent cations, but blocked by La3+. Single-channel recording revealed a permanently open state, with the same unitary conductance irrespective of whether cells expressed latrophilin or neurexin. Therefore, while pore formation displayed differences consistent with the reported properties of alpha-latrotoxin binding to latrophilin and neurexin, the pores induced by alpha-latrotoxin had identical properties. These results suggest that after anchoring to either of its nerve terminal receptors, alpha-latrotoxin inserts into the membrane and constitutes a single type of transmembrane ion pore.
Van Renterghem
C
C
Laboratoire de Neurobiologie des Canaux Ioniques, INSERM U464, Faculté de Médecine Secteur Nord, Boulevard Pierre Dramard, F-13916 Marseille Cedex 20, France. vanr.c@jean-roche.univ-mrs.fr
Iborra
C
C
Martin-Moutot
N
N
Lelianova
V
V
Ushkaryov
Y
Y
Seagar
M
M
D000818:Animals; D001921:Brain / Q000502:physiology*; D002118:Calcium / Q000502:physiology*; D002460:Cell Line; D002463:Cell Membrane Permeability; D006224:Cricetinae; D004533:Egtazic Acid / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology*; D051381:Rats; D018000:Receptors, Peptide / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D013111:Spider Venoms / Q000494:pharmacology*; D014162:Transfection
D009419:Nerve Tissue Proteins; D018000:Receptors, Peptide; D013111:Spider Venoms; C034800:alpha-latrotoxin receptor; D004533:Egtazic Acid; C020763:alpha-latrotoxin; D002118:Calcium