Strategic location of calcium channels at transmitter release sites of frog neuromuscular synapses.
The localization of Ca2+ channels relative to the position of transmitter release sites was investigated at the frog neuromuscular junction (NMJ). Ca2+ channels were labeled with fluorescently tagged omega-conotoxin GVIA, an irreversible Ca2+ channel ligand, and observed with a confocal laser scanning microscope. The Ca2+ channel labeling almost perfectly matched that of acetylcholine receptors which were labeled with fluorescent alpha-bung-arotoxin. This indicates that groups of Ca2+ channels are localized exclusively at the active zones of the frog NMJ. Cross sections of NMJs showed that Ca2+ channels are clustered on the presynaptic membrane adjacent to the postsynaptic membrane.
Robitaille
R
R
Department of Physiology, University of Toronto, Ontario, Canada.
Adler
E M
EM
Charlton
M P
MP
D000818:Animals; D001710:Biotin; D002038:Bungarotoxins / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D005456:Fluorescent Dyes; D008978:Mollusk Venoms / Q000378:metabolism; D009469:Neuromuscular Junction / Q000378:metabolism* / Q000502:physiology; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011894:Rana pipiens; D011950:Receptors, Cholinergic / Q000032:analysis / Q000378:metabolism; D013569:Synapses / Q000378:metabolism* / Q000502:physiology; D020866:omega-Conotoxin GVIA
D002038:Bungarotoxins; D015220:Calcium Channels; D005456:Fluorescent Dyes; D008978:Mollusk Venoms; D018377:Neurotransmitter Agents; D011950:Receptors, Cholinergic; D001710:Biotin; D020866:omega-Conotoxin GVIA