Department of Animal Physiology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland; Department of Cell Biology, Nencki Institute of Experimental Biology PAS, 3 Pasteur Street, 02-093 Warsaw, Poland.
Eur J Protistol. 2013 Nov;49(4):564-74. doi: 10.1016/j.ejop.2013.05.004. Epub 2013 Jul 18.
In Tetrahymena, besides apparent cell polarity generated by specialized cortical structures, several proteins display a specific asymmetric distribution suggesting their involvement in the generation and the maintenance of cell polarization. One of these proteins, a membrane skeleton protein called fenestrin, forms an antero-posterior gradient, and is accepted as a marker of cell polarity during different cellular processes, such as cell division or oral replacement. In conjugating cells, fenestrin forms an intracytoplasmic net which participates in pronuclear exchange. The function of fenestrin is still unknown. To better understand the role of fenestrin we characterized this protein in an amicronuclear Tetrahymena pyriformis. We show that in this ciliate not only does fenestrin localization change in a cell division-dependent manner, but its mRNA and protein level is also cell cycle-regulated. We determine that the two available anti-fenestrin antibodies, 3A7 and 9A7, recognize different pools of fenestrin isoforms, and that 9A7 is the more general. In addition, our results indicate that fenestrin is a phosphoprotein. We also show that the level of fenestrin in the amicronuclear T. pyriformis and the amicronuclear BI3840 strain of T. thermophila is several times lower than in micronuclear T. thermophila.
在四膜虫中，除了由专门的皮质结构产生的明显的细胞极性外，还有几种蛋白质表现出特定的不对称分布，表明它们参与了细胞极性的产生和维持。这些蛋白质之一是一种叫做窗格蛋白的膜骨架蛋白，它形成前后梯度，并被接受为细胞极性的标志物，参与细胞分裂或口器替换等不同的细胞过程。在接合细胞中，窗格蛋白形成细胞质内的网络，参与原核交换。窗格蛋白的功能尚不清楚。为了更好地理解窗格蛋白的作用，我们在一种无核四膜虫中对这种蛋白质进行了表征。我们表明，在这种纤毛虫中，窗格蛋白的定位不仅以细胞分裂依赖的方式发生变化，而且其 mRNA 和蛋白质水平也受细胞周期调控。我们确定了两种可用的抗窗格蛋白抗体 3A7 和 9A7 识别不同的窗格蛋白同工型池，并且 9A7 更具通用性。此外，我们的结果表明窗格蛋白是一种磷酸化蛋白。我们还表明，无核四膜虫和嗜热四膜虫 BI3840 株的窗格蛋白水平比有核嗜热四膜虫低几倍。
