ACTIN POLYMERIZATION INDUCED BY A MOTILITY-RELATED HIGH-AFFINITY CYTOCHALASIN BINDING COMPLEX FROM HUMAN-ERYTHROCYTE MEMBRANE
ACTIN POLYMERIZATION INDUCED BY A MOTILITY-RELATED HIGH-AFFINITY CYTOCHALASIN BINDING COMPLEX FROM HUMAN-ERYTHROCYTE MEMBRANE
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DOI：
10.1073/pnas.76.5.2345
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发表时间：
1979-01-01
影响因子：
11.1
通讯作者：
LIN, S
中科院分区：
文献类型：
--
作者：
LIN, DC;LIN, S
高MW复合物（沉降系数约为0.0001）。用蔗糖密度梯度离心法从人红细胞膜的低离子强度提取物中分离得到一个含有[3 H]二氢细胞松弛素B高亲和力结合位点的蛋白（27 S）。十二烷基硫酸钠/聚丙烯酰胺凝胶电泳显示，肌动蛋白，血影蛋白和其他次要成分，包括2个多肽的电泳迁移率带4.1，存在于复合物含有馏分。在低离子强度介质中，将该复合物加入到肌肉单体肌动蛋白（G-肌动蛋白）的溶液中，导致粘度迅速增加至与丝状肌动蛋白（F-肌动蛋白）的溶液相当的水平。电镜显示粘度增加反映了肌动蛋白丝的形成。诱导的肌动蛋白聚合的速率取决于加到G-肌动蛋白中的复合物的量;在< 1小时内，来自含复合物级分的< 1 μ g蛋白质诱导0.4mg G-肌动蛋白转化为F型。结合研究表明，聚合后的肌动蛋白的细胞松弛素结合复合物成为与肌动蛋白丝。低浓度的细胞松弛素D和E和二氢细胞松弛素B抑制复合物诱导的肌动蛋白聚合;药物在抑制该过程中的相对效力对应于它们对复合物的相对亲和力和它们在影响细胞运动中的相对效力。细胞松弛素结合复合物通过控制细胞中肌动蛋白微丝的形成和膜附着，显然起着细胞运动的调节位点的作用。
A high MW complex (sedimentation coefficient .apprxeq. 27 S) containing high-affinity binding site for [3H]dihydrocytochalasin B was isolated from a low ionic strength extract of human erythrocyte membranes by sucrose density gradient centrifugation. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis showed that actin, spectrin and other minor components, including 2 polypeptides with the electrophoretic mobility of band 4.1, were present in the complex-containing fraction. Addition of this complex to a solution of muscle monomeric actin (G-actin) in a low ionic strength medium caused a rapid increase in viscosity to a level comparable to that of a solution of filamentous actin (F-actin). EM showed that the viscosity increase reflected actin filament formation. The rate of induced actin polymerization was dependent on the amount of complex added to the G-actin; in < 1 h, < 1 .mu.g of protein from the complex-containing fraction induced the conversion of 0.4 mg of G-actin to the F form. Binding studies indicated that upon polymerization of the actin the cytochalasin binding complex became associated with the actin filaments. Low concentration of cytochalasins D and E and dihydrocytochalasin B inhibited actin polymerization induced by the complex; the relative potencies of the drugs in inhibiting this process corresponded to their relative affinities for the complex and their relative potencies in affecting cell motility. The cytochalasin binding complex apparently functions as a regulatory site for cell motility by controlling formation and membrane attachment of actin-containing microfilaments in the cell.