A spider toxin, ω-agatoxin IV A, binds to fixed as well as living tissues: cytochemical visualization of P/Q-type calcium channels.
ω-Agatoxin IV A, a peptidyl toxin from Agelenopsis aperta venom, selectively binds to voltage-gated P/Q-type calcium channels. ω-Agatoxin IV A has been used as a selective tool in pharmacological and electrophysiological studies. Visualization of P/Q-type calcium channels has previously been accomplished using biotin-conjugated ω-Agatoxin IV A in freshly prepared mouse cerebellar and hippocampal slices (Nakanishi et al, J. Neurosci. Res., 41: , 532, 1995). Here biotinylated ω-agatoxin IV A was applied to transcardially fixed brain slices prepared with various fixatives. ω-Agatoxin IV A did not bind to fixed tissues from P/Q-type calcium channel knockout mice, confirming that binding to normal, fixed tissues was not an artifact. Using transmission electron microscopy, locations of biotinylated ω-agatoxin IV A binding sites visualized with gold-conjugated streptavidin showed a similar pattern to those visualized with antibody. The ability of biotinylated ω-agatoxin IV A to bind to fixed tissue provides a new cytochemical technique to study molecular architecture of synapses.
Structural Cellular Biology Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1, Tancha, Onna-son, Kunigami-gun, Okinawa 904-0412, Japan nakanishi_s@oist.jp.
Setsuko
S
Nakanishi
D060848:Agatoxins / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D019921:Biotinylation; D001933:Brain Stem / Q000502:physiology; D020865:Calcium Channels, P-Type / Q000378:metabolism*; D020907:Calcium Channels, Q-Type / Q000378:metabolism*; D051379:Mice; D046529:Microscopy, Electron, Transmission / Q000379:methods; D016253:Microscopy, Immunoelectron / Q000379:methods; D009474:Neurons / Q000502:physiology; D011485:Protein Binding; D051381:Rats; D019809:Streptavidin / Q000737:chemistry; D013569:Synapses / Q000378:metabolism*; D016707:Tissue Fixation
D060848:Agatoxins; D020865:Calcium Channels, P-Type; D020907:Calcium Channels, Q-Type; D019809:Streptavidin
P/Q-type calcium channels; auditory brainstem; cytochemical visualization; fixed brain; synapse; ω-agatoxin IV A