Wang Pengwei, Hawkins Timothy J, Richardson Christine, Cummins Ian, Deeks Michael J, Sparkes Imogen, Hawes Chris, Hussey Patrick J
School of Biological and Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE, UK.
Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Headington, Oxford OX3 0BP, UK.
Curr Biol. 2014 Jun 16;24(12):1397-1405. doi: 10.1016/j.cub.2014.05.003. Epub 2014 Jun 5.
The cortical endoplasmic reticulum (ER) network in plants is a highly dynamic structure, and it contacts the plasma membrane (PM) at ER-PM anchor/contact sites. These sites are known to be essential for communication between the ER and PM for lipid transport, calcium influx, and ER morphology in mammalian and fungal cells. The nature of these contact sites is unknown in plants, and here, we have identified a complex that forms this bridge. This complex includes (1) NET3C, which belongs to a plant-specific superfamily (NET) of actin-binding proteins, (2) VAP27, a plant homolog of the yeast Scs2 ER-PM contact site protein, and (3) the actin and microtubule networks. We demonstrate that NET3C and VAP27 localize to puncta at the PM and that NET3C and VAP27 form homodimers/oligomers and together form complexes with actin and microtubules. We show that F-actin modulates the turnover of NET3C at these puncta and microtubules regulate the exchange of VAP27 at the same sites. Based on these data, we propose a model for the structure of the plant ER-PM contact sites.
植物中的皮质内质网（ER）网络是一种高度动态的结构，它在内质网-质膜（PM）锚定/接触位点与质膜接触。已知这些位点对于哺乳动物和真菌细胞中内质网与质膜之间脂质运输、钙内流以及内质网形态的通讯至关重要。在植物中，这些接触位点的性质尚不清楚，在此，我们鉴定出了形成这座桥梁的一个复合体。该复合体包括：（1）NET3C，它属于肌动蛋白结合蛋白的植物特异性超家族（NET）；（2）VAP27，酵母Scs2内质网-质膜接触位点蛋白的植物同源物；（3）肌动蛋白和微管网络。我们证明NET3C和VAP27定位于质膜上的点状结构，并且NET3C和VAP27形成同型二聚体/寡聚体，并与肌动蛋白和微管一起形成复合体。我们表明，F-肌动蛋白调节这些点状结构处NET3C的周转，微管调节相同位点处VAP27的交换。基于这些数据，我们提出了一个植物内质网-质膜接触位点结构的模型。
