Cuneo P, Magri E, Verzola A, Grazi E
Instituto di Chimica Biologica, Università di Ferrara, Italy.
Biochem J. 1992 Jan 15;281 ( Pt 2)(Pt 2):507-12. doi: 10.1042/bj2810507.
We propose that, in the cell, the reversible conversion of actin filaments into actin bundles is controlled by the concentration of the macromolecules [we have employed poly(ethylene glycol) 6000 to mimic the macromolecules of the cell] as well as by the nature of the ancillary cytoskeletal proteins that decorate actin filaments. The proposal is based on the following evidence. (1) Under our experimental conditions the transition from filaments into bundles occurs at increasing concentrations of poly(ethylene glycol), with the following sequence: caldesmon-actin, 3%; filamin-actin, 4-5%; caldesmon-tropomyosin-actin, 5-7%; actin, 6-7%; tropomyosin-actin, 9-10%. (2) Under conditions of low osmoelastic stress [3% poly(ethylene glycol)], preformed caldesmon-actin bundles are dissociated by the addition of either tropomyosin or tropomyosin-decorated actin. The dissociation of the bundles promoted by the addition of tropomyosin-decorated actin is faster than that promoted by the addition of tropomyosin.
我们提出，在细胞中，肌动蛋白丝向肌动蛋白束的可逆转化受大分子（我们使用聚乙二醇6000来模拟细胞中的大分子）浓度以及修饰肌动蛋白丝的辅助细胞骨架蛋白性质的控制。该提议基于以下证据。（1）在我们的实验条件下，随着聚乙二醇浓度的增加，会发生从丝到束的转变，顺序如下：钙调蛋白-肌动蛋白，3%；细丝蛋白-肌动蛋白，4-5%；钙调蛋白-原肌球蛋白-肌动蛋白，5-7%；肌动蛋白，6-7%；原肌球蛋白-肌动蛋白，9-10%。（2）在低渗透弹性应力条件下（3%聚乙二醇），预先形成的钙调蛋白-肌动蛋白束会因添加原肌球蛋白或原肌球蛋白修饰的肌动蛋白而解离。添加原肌球蛋白修饰的肌动蛋白促进的束解离比添加原肌球蛋白促进的更快。
