Ueki Shoko, Citovsky Vitaly
Institute of Plant Science and Resources; Okayama University; Chuo, Kurashiki, Okayama Japan.
Department of Biochemistry and Cell Biology; State University of New York; Stony Brook, NY USA.
Plant Signal Behav. 2014;9(2):e27899. doi: 10.4161/psb.27899. Epub 2014 Feb 11.
Encased in rigid cell walls, plant cells have evolved unique channel structures, plasmodesma (Pd), to create a pathway for molecular exchange between adjacent cells. Pd are basically cytoplasmic channels through the cell wall, which are lined by plasma membrane, and contain a modified strand of ER that spans them. These structures provide cytoplasmic and membrane continuity between connected cells, and that continuity is utilized for short and long distance molecular trafficking. Pd sphincters, made from constricting the Pd openings by outer layers of callose, together with the ER strand that occludes the Pd lumen set the upper limit for the size of molecules that can freely diffuse through the cytoplasmic component of the Pd channel. This limit, called the size exclusion limit (SEL), is a major factor that restricts macromolecular transport through Pd.
植物细胞被包裹在坚硬的细胞壁中，进化出了独特的通道结构——胞间连丝（Pd），以形成相邻细胞间分子交换的途径。胞间连丝本质上是穿过细胞壁的细胞质通道，由质膜排列，并且包含一条横跨它们的内质网修饰链。这些结构在相连细胞之间提供了细胞质和膜的连续性，并且这种连续性被用于短距离和长距离的分子运输。由胼胝质外层收缩胞间连丝开口形成的胞间连丝括约肌，连同堵塞胞间连丝腔的内质网链，设定了能够自由扩散通过胞间连丝通道细胞质成分的分子大小上限。这个限度称为大小排阻极限（SEL），是限制大分子通过胞间连丝运输的一个主要因素。
