TUBULIN AGGREGATION AND DISAGGREGATION - MEDIATION BY 2 DISTINCT VINBLASTINE-BINDING SITES
TUBULIN AGGREGATION AND DISAGGREGATION - MEDIATION BY 2 DISTINCT VINBLASTINE-BINDING SITES
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DOI：
10.1073/pnas.73.7.2375
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发表时间：
1976-01-01
影响因子：
11.1
通讯作者：
WOLFF, J
中科院分区：
文献类型：
--
作者：
BHATTACHARYYA, B;WOLFF, J
大鼠脑微管蛋白每个分子具有2个不同的长春碱结合位点：一个高亲和性位点，亲和常数为6.2 × 104。106 M-1的低亲和性位点和亲和常数为8 × 106 M-1的低亲和性位点。104 M-1高亲和力位点不稳定，t1/237 °。的3.5小时，秋水仙素的保护和盐的影响，而低亲和力的网站是稳定的，但被盐抑制。与这两个位点的结合是快速的。长春碱与微管蛋白的高亲和性结合常数（6.2 × 104）。106 M-1）对应于体外防止微管蛋白聚合所需的长春碱的半最大浓度，而低亲和力结合常数（8 × 106 M-1）对应于体外抑制微管蛋白聚合所需的长春碱的半最大浓度。104 M-1）对应于聚集微管蛋白所需的长春碱的半数最大浓度。长春碱结合到高和低亲和力的网站，分别，可能占微管蛋白的解聚和聚集行为。
Rat brain tubulin possessed 2 distinct binding sites for vinblastine per molecule: a high-affinity site with an affinity constant of 6.2 .times. 106 M-1 and a low-affinity site with an affinity constant of 8 .times. 104 M-1. The high-affinity site was labile with a t1/237.degree. of 3.5 h, protected by colchicine and unaffected by salt, whereas the low-affinity site was stable but was inhibited by salt. Binding to both sites was rapid. The high-affinity binding constant of vinblastine to tubulin (6.2 .times. 106 M-1) corresponded to the half-maximal concentration of vinblastine needed to prevent polymerization of tubulin in vitro, whereas the low-affinity binding constant (8 .times. 104 M-1) corresponds to the half-maximal concentration of vinblastine required to aggregate tubulin. Vinblastine binding to the high- and low-affinity sites, respectively, probably accounts for the depolymerization and aggregation behavior of tubulin.