omega-Conotoxin and Cd2+ stimulate the recruitment to the plasmamembrane of an intracellular pool of voltage-operated Ca2+ channels.
125I-omega-conotoxin binding to neuroblastoma cells at 37 degrees C continuously increased, reaching a plateau after 6-8 hr; this was up to 6 times higher than that observed at lower temperatures. The same effect was induced by short pulses with omega-conotoxin followed by a chase period at 37 degrees C in control medium. Cd2+ also induced up-regulation of surface 125I-omega-conotoxin-binding sites. Fura-2 and patch-clamp experiments showed that the recruited binding sites corresponded to functional voltage-operated Ca2+ channels. Permeabilization experiments revealed a large intracellular pool of 125I-omega-conotoxin-binding sites, whose recruitment to the plasmamembrane was prevented by brefeldin A and nocodazole. These data suggest that specific stimuli might induce voltage-operated Ca2+ channel translocation to plasmamembrane and, in this way, modulate presynaptic events.
Passafaro
M
M
Department of Medical Pharmacology, University of Milan, Italy.
Clementi
F
F
Pollo
A
A
Carbone
E
E
Sher
E
E
D001665:Binding Sites / Q000187:drug effects; D001692:Biological Transport; D002104:Cadmium / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism*; D002463:Cell Membrane Permeability; D004594:Electrophysiology; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D007700:Kinetics; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D020866:omega-Conotoxin GVIA
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D010455:Peptides; D002104:Cadmium; D020866:omega-Conotoxin GVIA