Kropf D L, Bisgrove S R, Hable W E
University of Utah, Department of Biology, Salt Lake City 84112-0840, USA.
Curr Opin Cell Biol. 1998 Feb;10(1):117-22. doi: 10.1016/s0955-0674(98)80094-x.
There are two quite different modes of polar cell expansion in plant cells, namely, diffuse growth and tip growth. The direction of diffuse growth is determined by the orientation of cellulose microfibrils in the cell wall, which in turn are aligned by microtubules in the cell cortex. The orientation of the cortical microtubule array changes in response to developmental and environmental signals, and recent evidence indicates that microtubule disassembly/reassembly and microtubule translocation participate in reorientation of the array. Tip growth, in contrast, is governed mainly by F-actin, which has several putative forms and functions in elongating cells. Longitudinal cables are involved in vesicle transport to the expanding apical dome and, in some tip growers, a subapical ring of F-actin may participate in wall-membrane adhesions. The structure and function of F-actin within the apical dome may be variable, ranging from a dense meshwork to sparse single filaments. The presence of multiple F-actin structures in elongating tips suggests extensive regulation of this cytoskeletal array.
植物细胞中存在两种截然不同的极性细胞扩张模式，即扩散生长和顶端生长。扩散生长的方向由细胞壁中纤维素微纤丝的取向决定，而纤维素微纤丝又由细胞皮层中的微管排列对齐。皮层微管阵列的取向会根据发育和环境信号而变化，最近的证据表明微管的拆卸/重新组装以及微管易位参与了该阵列的重新定向。相比之下，顶端生长主要由F-肌动蛋白控制，F-肌动蛋白在伸长细胞中有几种假定的形式和功能。纵向束参与囊泡向不断扩展的顶端圆顶的运输，并且在一些顶端生长的细胞中，F-肌动蛋白的亚顶端环可能参与壁-膜粘连。顶端圆顶内F-肌动蛋白的结构和功能可能各不相同，从密集的网络到稀疏的单丝。伸长顶端中多种F-肌动蛋白结构的存在表明对这种细胞骨架阵列有广泛的调控。
