Gardiner J, Marc J
School of Biological Sciences, University of Sydney, Sydney, New South Wales, Australia.
Protoplasma. 2003 Sep;222(1-2):61-74. doi: 10.1007/s00709-003-0009-3.
Plant microtubule-associated proteins (MAPs) are important in modulating the function of the microtubule cytoskeleton. Various plant MAPs have already been described. However, because of the complexity of the plant microtubule cytoskeleton and its responses to developmental and environmental stimuli, there are undoubtedly many more MAPs to be discovered. We have used a literature search and the BLAST protein comparison program to identify which model MAPs from other taxa have close homologues in Arabidopsis thaliana. The search revealed Arabidopsis homologues of 14 model MAPs, with E values (numbers of proteins that will match the model protein merely by chance) of <1 x 10(-10) and homologous domains spanning 98-599 amino acid residues, representing 57.1-97.0% of the model MAP sequence, as well as 22.5-72.8% amino acid identities and 76.3-96.2% conservation of secondary structure in the homologous domain. All of the Arabidopsis homologues have either a full cDNA clone or an expressed sequence tag in the GenBank database and therefore are expressed. The proteins are likely to regulate a variety of functions, including tubulin folding, microtubule nucleation and polymerisation dynamics, microtubule-dependent cell cycle control, organisation of microtubule arrays, interaction of microtubules with plasma-membrane-associated protein complexes, and interactions with various other proteins. The exact functions of these putative MAPs in the plant cell remain to be elucidated empirically. The identification of these putative MAPs opens new avenues for the investigation of the complexities of the plant microtubule cytoskeleton.
植物微管相关蛋白（MAPs）在调节微管细胞骨架的功能方面起着重要作用。各种植物MAPs已被描述。然而，由于植物微管细胞骨架的复杂性及其对发育和环境刺激的反应，无疑还有更多的MAPs有待发现。我们通过文献检索和BLAST蛋白比较程序来确定来自其他分类群的哪些模型MAPs在拟南芥中有密切的同源物。搜索结果显示了14种模型MAPs的拟南芥同源物，其E值（仅因偶然因素与模型蛋白匹配的蛋白质数量）<1×10⁻¹⁰，同源结构域跨越98 - 599个氨基酸残基，占模型MAP序列的57.1 - 97.0%，同源结构域中的氨基酸同一性为22.5 - 72.8%，二级结构的保守性为76.3 - 96.2%。所有拟南芥同源物在GenBank数据库中都有完整的cDNA克隆或表达序列标签，因此都是有表达的。这些蛋白质可能调节多种功能，包括微管蛋白折叠、微管成核和聚合动力学、微管依赖性细胞周期控制、微管阵列的组织、微管与质膜相关蛋白复合物的相互作用以及与各种其他蛋白质的相互作用。这些假定的MAPs在植物细胞中的具体功能仍有待通过实验来阐明。这些假定的MAPs的鉴定为研究植物微管细胞骨架的复杂性开辟了新途径。
