Gardiner John C, Taylor Neil G, Turner Simon R
School of Biological Sciences, University of Manchester, Manchester M13 9PT, United Kingdom.
Plant Cell. 2003 Aug;15(8):1740-8. doi: 10.1105/tpc.012815.
Cellulose synthesis in the developing xylem vessels of Arabidopsis requires three members of the cellulose synthase (CesA) gene family. In young vessels, these three proteins localize within the cell, whereas in older vessels, all three CesA proteins colocalize with bands of cortical microtubules that mark the sites of secondary cell wall deposition. In the absence of one subunit, however, the remaining two subunits are retained in the cell, demonstrating that all three CesA proteins are required to assemble a functional complex. CesA proteins with altered catalytic activity localize normally, suggesting that cellulose synthase activity is not required for this localization. Cortical microtubule arrays are required continually to maintain normal CesA protein localization. By contrast, actin microfilaments do not colocalize with the CesA proteins and are unlikely to play a direct role in their localization. Green fluorescent protein-tagged CesA reveals a novel process in which the structure and/or local environment of the cellulose synthase complex is altered rapidly.
拟南芥发育中的木质部导管中的纤维素合成需要纤维素合酶（CesA）基因家族的三个成员。在幼嫩导管中，这三种蛋白质定位于细胞内，而在成熟导管中，所有三种CesA蛋白质都与标记次生细胞壁沉积部位的皮层微管带共定位。然而，在缺少一个亚基的情况下，其余两个亚基保留在细胞中，这表明组装功能复合体需要所有三种CesA蛋白质。具有改变的催化活性的CesA蛋白质正常定位，这表明这种定位不需要纤维素合酶活性。需要持续的皮层微管阵列来维持正常的CesA蛋白质定位。相比之下，肌动蛋白微丝不与CesA蛋白质共定位，不太可能在其定位中起直接作用。绿色荧光蛋白标记的CesA揭示了一个新过程，其中纤维素合酶复合体的结构和/或局部环境迅速改变。
