Hirono M, Kumagai Y, Numata O, Watanabe Y
Institute of Biological Sciences, University of Tsukuba, Ibaraki, Japan.
Proc Natl Acad Sci U S A. 1989 Jan;86(1):75-9. doi: 10.1073/pnas.86.1.75.
Actin from Tetrahymena pyriformis has been purified by monitoring the presence of the actin gene product with an antiserum against a synthetic N-terminal peptide deduced from the nucleotide sequence of the Tetrahymena actin gene that we cloned previously. This highly purified Tetrahymena actin shares many essential properties with ubiquitous actin, including ion-dependent polymerization to microfilaments, binding with muscle heavy meromyosin to form arrowheads, and activation of the Mg2+-ATPase of muscle myosin subfragment 1. On the other hand, some properties of this purified Tetrahymena actin clearly differ from those of muscle actin: (i) Tetrahymena actin has 8 times less ability to activate the Mg2+-ATPase of muscle myosin subfragment 1 than muscle actin; (ii) Tetrahymena actin did not bind to phalloidin at all; (iii) Tetrahymena actin did not inhibit DNase I activity at all. In general, Tetrahymena actin has very unusual properties when compared to other actins described so far. This actin is expected to provide important clues for elucidating problems concerning the relationships between the structural and functional domains in an actin molecule.
通过使用针对我们先前克隆的梨形四膜虫肌动蛋白基因核苷酸序列推导的合成N端肽的抗血清监测肌动蛋白基因产物的存在，已纯化了梨形四膜虫的肌动蛋白。这种高度纯化的梨形四膜虫肌动蛋白与普遍存在的肌动蛋白具有许多基本特性，包括离子依赖性聚合成微丝、与肌肉重酶解肌球蛋白结合形成箭头状以及激活肌肉肌球蛋白亚片段1的Mg2 + -ATP酶。另一方面，这种纯化的梨形四膜虫肌动蛋白的一些特性明显不同于肌肉肌动蛋白：（i）梨形四膜虫肌动蛋白激活肌肉肌球蛋白亚片段1的Mg2 + -ATP酶的能力比肌肉肌动蛋白低8倍；（ii）梨形四膜虫肌动蛋白根本不与鬼笔环肽结合；（iii）梨形四膜虫肌动蛋白根本不抑制DNase I活性。一般而言，与迄今为止描述的其他肌动蛋白相比，梨形四膜虫肌动蛋白具有非常不寻常的特性。这种肌动蛋白有望为阐明肌动蛋白分子中结构域与功能域之间关系的问题提供重要线索。
