Taylor D L, Condeelis J S, Rhodes J A
Prog Clin Biol Res. 1977;17:581-603.
Motile extracts from D, discoideum and A. proteus have been characterized in order to compare the structural dynamics and chemical regulation of movement in 2 different types of amoeboid cells. The structural dynamics of both extracts involve the formation of a nonmotile cytoskeleton followed by the contraction of actin and myosin to generate both direct contractile force and cytoplasmic streaming. The contractions are regulated by calcium ions and a threshold of ca. 1.0 X 10(-6) M calcium induces a transformation of actin to the free F-actin state which is capable of interacting with myosin. Furthermore, 3 low molecular weight proteins are concentrated along with actin and myosin during contraction and might play a regulatory role in movement. Several common characteristics of amoeba cytoplasm have been exhibited by these two types of amoeboid cells. The major contractile and "associated" proteins are similar, actin and associated proteins are structurally dynamic, and movement is regulated by calcium. The different modes of movement observed in different types of amoeboid cells could result from the site, rate, and extent of actin transformation followed in some regions by contractions.
已对盘基网柄菌和变形虫的运动提取物进行了表征，以便比较两种不同类型变形虫细胞中运动的结构动力学和化学调节。两种提取物的结构动力学都涉及形成非运动性细胞骨架，随后肌动蛋白和肌球蛋白收缩，以产生直接收缩力和细胞质流动。收缩由钙离子调节，约1.0×10⁻⁶ M的钙阈值会诱导肌动蛋白转变为能够与肌球蛋白相互作用的游离F-肌动蛋白状态。此外，在收缩过程中，有3种低分子量蛋白质与肌动蛋白和肌球蛋白一起浓缩，可能在运动中起调节作用。这两种变形虫细胞展现出了变形虫细胞质的几个共同特征。主要的收缩蛋白和“相关”蛋白相似，肌动蛋白和相关蛋白在结构上是动态的，并且运动受钙调节。在不同类型变形虫细胞中观察到的不同运动模式可能是由肌动蛋白转化的位点、速率和程度导致的，在某些区域随后会发生收缩。
