Hillmer S, Movafeghi A, Robinson D G, Hinz G
Department of Structural Cell Physiology, Albrecht-von-Haller Institute for Plant Sciences, University of Göttingen, 37073 Göttingen, Germany.
J Cell Biol. 2001 Jan 8;152(1):41-50. doi: 10.1083/jcb.152.1.41.
Developing pea cotyledons contain functionally different vacuoles, a protein storage vacuole and a lytic vacuole. Lumenal as well as membrane proteins of the protein storage vacuole exit the Golgi apparatus in dense vesicles rather than in clathrin-coated vesicles (CCVs). Although the sorting receptor for vacuolar hydrolases BP-80 is present in CCVs, it is not detectable in dense vesicles. To localize these different vacuolar sorting events in the Golgi, we have compared the distribution of vacuolar storage proteins and of alpha-TIP, a membrane protein of the protein storage vacuole, with the distribution of the vacuolar sorting receptor BP-80 across the Golgi stack. Analysis of immunogold labeling from cryosections and from high pressure frozen samples has revealed a steep gradient in the distribution of the storage proteins within the Golgi stack. Intense labeling for storage proteins was registered for the cis-cisternae, contrasting with very low labeling for these antigens in the trans-cisternae. The distribution of BP-80 was the reverse, showing a peak in the trans-Golgi network with very low labeling of the cis-cisternae. These results indicate a spatial separation of different vacuolar sorting events in the Golgi apparatus of developing pea cotyledons.
发育中的豌豆子叶含有功能不同的液泡，即蛋白储存液泡和溶酶液泡。蛋白储存液泡的腔蛋白和膜蛋白以致密小泡而非网格蛋白包被小泡（CCV）的形式从高尔基体中排出。尽管液泡水解酶分选受体BP - 80存在于CCV中，但在致密小泡中却检测不到。为了在高尔基体中定位这些不同的液泡分选事件，我们比较了液泡储存蛋白和α - TIP（蛋白储存液泡的一种膜蛋白）的分布与液泡分选受体BP - 80在整个高尔基体堆叠中的分布。对冷冻切片和高压冷冻样品的免疫金标记分析显示，高尔基体堆叠中储存蛋白的分布存在陡峭梯度。顺面膜囊对储存蛋白的标记强烈，而反面膜囊对这些抗原的标记非常低。BP - 80的分布则相反，在反式高尔基体网络中出现峰值，而顺面膜囊的标记非常低。这些结果表明，发育中的豌豆子叶高尔基体中不同液泡分选事件存在空间分离。
