Lishko V K, Gimmel'reĭkh N G, Nikolishina E V
Ukr Biokhim Zh (1978). 1989 Nov-Dec;61(6):22-7.
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.
研究了[125I]α- 拉毒素与大鼠脑突触体的结合情况。结果表明，在37℃时，毒素与突触体受体的结合恒定速率为8.2±1.3×10(7) M-1·s-1，而与突触体膜的结合速率为 -7.6±2.7×10(6) M-1·s-1。55 mM KCl诱导的突触体膜去极化降低了毒素与受体的结合速率，速率常数为3.9±1.5×10(7) m-1·s-1。突触体和突触体膜的毒素 - 受体复合物解离过程模式不同。在第一种情况下，解离分两个阶段进行，速率常数分别为3.6×10(-3) s-1和1.2×10(-4) s-1，在第二种情况下，解离为一个阶段，常数为2.0×10(-5) s-1。在改变由α- 拉毒素诱导的钙通量活性的试剂作用下，突触体上毒素结合位点的数量可能会发生变化。据推测，突触体中ATP水平的降低以及表面膜的去能化会导致α- 拉毒素受体状态的改变。
