Becker Burkhard, Doan Jean Michel, Wustman Brandon, Carpenter Eric J, Chen Li, Zhang Yong, Wong Gane K-S, Melkonian Michael
Biozentrum Köln, Botanical Institute, Universität zu Köln, Germany
Biozentrum Köln, Botanical Institute, Universität zu Köln, Germany.
Genome Biol Evol. 2015 May 14;7(6):1580-9. doi: 10.1093/gbe/evv089.
The extracellular matrix of scaly green flagellates consists of small organic scales consisting of polysaccharides and scale-associated proteins (SAPs). Molecular phylogenies have shown that these organisms represent the ancestral stock of flagellates from which all green plants (Viridiplantae) evolved. The molecular characterization of four different SAPs is presented. Three SAPs are type-2 membrane proteins with an arginine/alanine-rich short cytoplasmic tail and an extracellular domain that is most likely of bacterial origin. The fourth protein is a filamin-like protein. In addition, we report the presence of proteins similar to the integrin-associated proteins α-actinin (in transcriptomes of glaucophytes and some viridiplants), LIM-domain proteins, and integrin-associated kinase in transcriptomes of viridiplants, glaucophytes, and rhodophytes. We propose that the membrane proteins identified are the predicted linkers between scales and the cytoskeleton. These proteins are present in many green algae but are apparently absent from embryophytes. These proteins represent a new protein family we have termed gralins for green algal integrins. Gralins are absent from embryophytes. A model for the evolution of the cell surface proteins in Plantae is discussed.
鳞状绿藻鞭毛虫的细胞外基质由由多糖和鳞片相关蛋白（SAPs）组成的小有机鳞片构成。分子系统发育表明，这些生物代表了所有绿色植物（绿藻门）从中进化而来的鞭毛虫的祖先种群。本文介绍了四种不同SAPs的分子特征。三种SAPs是2型膜蛋白，具有富含精氨酸/丙氨酸的短细胞质尾巴和一个很可能起源于细菌的细胞外结构域。第四种蛋白是一种细丝蛋白样蛋白。此外，我们报告在绿藻门、一些绿藻植物以及红藻门的转录组中存在与整合素相关蛋白α-肌动蛋白（在蓝藻门和一些绿藻植物的转录组中）、LIM结构域蛋白和整合素相关激酶相似的蛋白。我们提出所鉴定的膜蛋白是鳞片与细胞骨架之间的预测连接物。这些蛋白存在于许多绿藻中，但在陆生植物中显然不存在。这些蛋白代表了一个我们称为绿藻整合素（gralins）的新蛋白家族。陆生植物中不存在绿藻整合素。本文还讨论了植物细胞表面蛋白的进化模型。
