Interconversion of structural and contractile actin gels by insertion of myosin during assembly.
Interconversion of structural and contractile actin gels by insertion of myosin during assembly.
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DOI：
10.1083/jcb.97.6.1745
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发表时间：
1983-12
期刊：
影响因子：
--
通讯作者：
Kane RE
中科院分区：
文献类型：
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作者：
Kane RE
海胆卵的可溶性细胞质蛋白的提取物形成不同组成和性质的凝胶，这取决于用于诱导肌动蛋白聚合的温度。在使肌球蛋白变性的温度下，形成由肌动蛋白、肌成束蛋白和220，000-mol-wt蛋白质组成的凝胶.肌成束蛋白将肌动蛋白结合成具有特征性带型的高度组织化的单位，这些肌动蛋白-肌成束蛋白单位是受精后形成的海胆微绒毛和海胆体腔细胞丝状足的结构核心。在较温和的条件下，形成更复杂的含肌球蛋白的凝胶，其在形成后一小时内收缩至其原始体积的一小部分。所谓的“结构”凝胶可以通过将肌动蛋白、肌成束蛋白和220，000-mol-wt蛋白质在50-100 mM KCl中组合来组装;本文报道的实验的目的是确定在组装过程中是否可以包括肌球蛋白，从而使结构凝胶和收缩凝胶相互转化。这种方法受到海胆肌球蛋白在凝胶组装中使用的低盐浓度下聚集的限制。已经设计了一种方法，用于在受控的KCl和ATP浓度下顺序组合这些组分，该方法允许形成含有分散的肌球蛋白的凝胶，最终浓度为60-100 mM KCl。这些凝胶在低ATP浓度（约10微米）下稳定，但在较高ATP浓度（约100微米）下收缩至小体积。收缩可以通过在低ATP下形成稳定的凝胶，然后将其覆盖上含有足够ATP的溶液来诱导收缩来控制。该系统为研究细胞质结构与运动性之间的相互关系提供了一个有用的模型。
Extracts of the soluble cytoplasmic proteins of the sea urchin egg form gels of different composition and properties depending on the temperature used to induce actin polymerization. At temperatures that inactivate myosin, a gel composed of actin, fascin, and a 220,000-mol- wt protein is formed. Fascin binds actin into highly organized units with a characteristic banding pattern, and these actin-fascin units are the structural core of the sea urchin microvilli formed after fertilization and of the urchin coelomocyte filopods. Under milder conditions a more complex myosin-containing gel is formed, which contracts to a small fraction of its original volume within an hour after formation. What has been called "structural" gel can be assembled by combining actin, fascin, and the 220,000-mol-wt protein in 50-100 mM KCl; the aim of the experiments reported here was to determine whether myosin could be included during assembly, thereby interconverting structural and contractile gel. This approach is limited by the aggregation of sea urchin myosin at the low salt concentrations utilized in gel assembly. A method has been devised for the sequential combination of these components under controlled KCl and ATP concentrations that allows the formation of a gel containing dispersed myosin at a final concentration of 60-100 mM KCl. These gels are stable at low (approximately 10 micron) ATP concentrations, but contract to a small volume in the presence of higher (approximately 100 micron) ATP. Contraction can be controlled by forming a stable gel at low ATP and then overlaying it with a solution containing sufficient ATP to induce contraction. This system may provide a useful model for the study of the interrelations between cytoplasmic structure and motility.