Polymerization of ADP-actin.
Polymerization of ADP-actin.
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DOI：
10.1083/jcb.99.3.769
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发表时间：
1984-09
期刊：
影响因子：
--
通讯作者：
Pollard TD
中科院分区：
文献类型：
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作者：
Pollard TD
使用己糖激酶、葡萄糖和ATP可逆地改变溶液中ADP和ATP的浓度，并与Acanthamoeba肌动蛋白结合，我测量了在50 mM KCl、1 mM MgCl2、1 mM EGTA、0.1 mM核苷酸、0.1 mM CaCl2、10 mM咪唑、pH 7中ATP-肌动蛋白和ADP-肌动蛋白的相对临界浓度和延伸率常数。通过稳态和延伸率方法，atp -肌动蛋白的临界浓度为0.1微米，adp -肌动蛋白的临界浓度为5微米。因此，5微米的肌动蛋白溶液可以通过从ATP到ADP再回到ATP的简单循环进行聚合、解聚和再聚合。关键浓度不同，因为atp -肌动蛋白的结合速率常数比adp -肌动蛋白高10倍，而解离速率常数比adp -肌动蛋白低5倍。这些结果表明ATP-肌动蛋白占据在ATP中生长的肌动蛋白丝的两端。结合的ATP必须在内部亚基上分裂，结合ATP的末端亚基的数量可能取决于生长速度。
Using hexokinase, glucose, and ATP to vary reversibly the concentrations of ADP and ATP in solution and bound to Acanthamoeba actin, I measured the relative critical concentrations and elongation rate constants for ATP-actin and ADP-actin in 50 mM KCl, 1 mM MgCl2, 1 mM EGTA, 0.1 mM nucleotide, 0.1 mM CaCl2, 10 mM imidazole, pH 7. By both steady-state and elongation rate methods, the critical concentrations are 0.1 microM for ATP-actin and 5 microM for ADP-actin. Consequently, a 5 microM solution of actin can be polymerized, depolymerized, and repolymerized by simply cycling from ATP to ADP and back to ATP. The critical concentrations differ, because the association rate constant is 10 times higher and the dissociation rate constant is five times lower for ATP-actin than ADP-actin. These results show that ATP-actin occupies both ends of actin filaments growing in ATP. The bound ATP must be split on internal subunits and the number of terminal subunits with bound ATP probably depends on the rate of growth.