[Binding of latrotoxin to synaptosomes and synaptic membranes of the rat brain].
The binding of [125I] alpha-latrotoxin to synaptosomes from the rat brain is studied. It is shown that the constant rate of toxin association with the synaptosome receptor at 37 degrees C is equal to 8.2 +/- 1.3 x 10(7) M-1.s-1, while that of synaptosomal membrane -7.6 +/- 2.7 x 10(6) M-1 s-1. Depolarization of the synaptosome membrane induced by 55 mM KCl decreases the binding rate of toxin to the receptor, the rate constant being equal to 3.9 +/- 1.5 x 10(7) m-1 s-1. The pattern of the dissociation process of the toxin-receptor complex of synaptosomes and of synaptosomal membrane is different. In the first case dissociation follows two stages with the rate constants 3.6 x 10(-3) s-1 and 1.2/10(-4) s-1, in the second case it follows one stage with the constant equalled 2.0 x 10(-5) s-1. The quantity of the toxin binding sites on synaptosomes may vary under the action of agents modifying the activity of calcium fluxes which are induced by alpha-latrotoxin. It is supposed that a decrease in the ATP level in synaptosomes as well as deenergy of the surface membrane leads to a change in the state of the alpha-latrotoxin receptor.
Lishko
V K
VK
Gimmel'reĭkh
N G
NG
Nikolishina
E V
EV
D000818:Animals; D001180:Arthropod Venoms / Q000378:metabolism*; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D007700:Kinetics; D051381:Rats; D017981:Receptors, Neurotransmitter / Q000378:metabolism; D013111:Spider Venoms / Q000378:metabolism*; D013570:Synaptic Membranes / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism*
D001180:Arthropod Venoms; D017981:Receptors, Neurotransmitter; D013111:Spider Venoms; C020763:alpha-latrotoxin
Sviazyvanie latrotoksina s sinaptosomami i sinaptocomal'nymi membranami mozga krys.