Identification and characterization of a novel microtubule-based motor associated with membranous organelles in tobacco pollen tubes
Identification and characterization of a novel microtubule-based motor associated with membranous organelles in tobacco pollen tubes
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DOI：
10.1105/tpc.12.9.1719
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发表时间：
2000-09-01
期刊：
影响因子：
11.6
通讯作者：
Cresti, M
中科院分区：
文献类型：
--
作者：
Cai, G;Romagnoli, S;Cresti, M
花粉管的生长取决于细胞器和囊泡沿花粉管的不同分布。微管在细胞器运动中的作用尚不确定，主要是因为分子水平上的信息有限。为了了解微管运动的分子基础，我们从烟草花粉管中分离出以atp依赖的方式与微管共同沉积的多肽。ATP从微管释放的主要多肽（ATP- maps）分子量为90、80和41 kD。一些研究结果表明，90-kD ATP- map是一个与激酶相关的马达：多肽与微管的结合被不可水解的ATP类似物AMP-PNP增强；90-kD多肽与针对激酶超家族运动结构域高度保守区域的肽抗体特异性反应；纯化的90-kD ATP-MAP诱导微管在体外运动试验中滑动；90 kd的ATP-MAP与微管激活的atp酶活性相关联。免疫定位研究表明，90-kD的ATP-MAP与花粉管皮质区与微管相关的细胞器结合。这些发现表明，90 kd的ATP-MAP是一种与运动蛋白相关的微管马达，在生长的花粉管皮层中移动细胞器。
Pollen tube growth depends on the differential distribution of organelles and vesicles along the tube. The role of microtubules in organelle movement is uncertain, mainly because information at the molecular level is limited. In an effort to understand the molecular basis of microtubule-based movement, we isolated from tobacco pollen tubes polypeptides that cosediment with microtubules in an ATP-dependent manner. Major polypeptides released from microtubules by ATP (ATP-MAPs) had molecular masses of 90, 80, and 41 kD. Several findings indicate that the 90-kD ATP-MAP is a kinesin-related motor: binding of the polypeptide to microtubules was enhanced by the nonhydrolyzable ATP analog AMP-PNP; the 90-kD polypeptide reacted specifically with a peptide antibody directed against a highly conserved region in the motor domain of the kinesin superfamily; purified 90-kD ATP-MAP induced microtubules to glide in motility assays in vitro; and the 90-kD ATP-MAP cofractionated with microtubule-activated ATPase activity. Immunolocalization studies indicated that the 90-kD ATP-MAP binds to organelles associated with microtubules in the cortical region of the pollen tube. These findings suggest that the 90-kD ATP-MAP is a kinesin-related microtubule motor that moves organelles in the cortex of growing pollen tubes.