Plant Molecular Biology Laboratory, TUBITAK, The Scientific and Technological Research Council of Turkey, Marmara Research Center, Genetic Engineering and Biotechnology Institute, Gebze, Kocaeli, Turkey.
Plant Biol (Stuttg). 2012 Jan;14(1):24-32. doi: 10.1111/j.1438-8677.2011.00482.x. Epub 2011 Jul 4.
ARF1 (ADP-ribosylation factor 1) and SAR1 (secretion-associated RAS super family) are involved in the formation and budding of vesicles throughout plant endomembrane systems. The molecular mechanisms of this transport have been studied extensively in mammalian and yeast cells. However, very little is known about the mechanisms of coat protein complex (COP) formation and recruitment of COP-vesicle cargoes in plants. To provide insights into vesicular trafficking in Pisum sativum L., we investigated mRNA and protein expression patterns of ARF1 and SAR1 in roots and shoots at early growth stages and in the de-etiolation process. We showed that ARF1 was concentrated mostly in the crude Golgi fractions, and SAR1 was concentrated predominantly in the crude ER fractions of de-etiolated shoots. ARF1 and SAR1 proteins were several times more abundant in shoots relative to roots. In total protein homogenates, the expression level of SAR1 and ARF1 was higher in shoots of dark-grown pea plants than light-grown plants. In contrast, ARF1 was higher in roots of light-grown pea relative to roots of dark-grown pea. With ageing, the ARF1 mRNA in roots was reduced, while SAR1 expression increased. Unlike ARF1 transcripts, ARF1 protein levels did not fluctuate significantly in root and shoot tissue during early development. The relative abundance of SAR1 protein in root tissues may suggest a high level of vesicular transport from the ER to the Golgi. Experimental results suggested that white light probably affects the regulation of ARF1 and SAR1 protein levels. On the other hand, short-term white light affects SAR1 but not ARF1.
ARF1（ADP-核糖基化因子 1）和 SAR1（与分泌相关的 RAS 超家族）参与植物内膜系统中囊泡的形成和出芽。在哺乳动物和酵母细胞中，已经对这种运输的分子机制进行了广泛的研究。然而，关于植物中 COP（衣壳蛋白复合物）形成和 COP-囊泡货物募集的机制知之甚少。为了深入了解豌豆中的囊泡运输，我们研究了 ARF1 和 SAR1 在早期生长阶段和去黄化过程中根和茎中的 mRNA 和蛋白质表达模式。我们表明，ARF1 主要集中在粗面内质网部分，SAR1 主要集中在去黄化茎的粗面内质网部分。ARF1 和 SAR1 蛋白在茎中的丰度相对于根高出数倍。在总蛋白匀浆中，与光照下生长的豌豆相比，黑暗生长的豌豆茎中的 SAR1 和 ARF1 表达水平更高。相比之下，光照下生长的豌豆根中的 ARF1 高于黑暗生长的豌豆根。随着衰老，根中的 ARF1 mRNA 减少，而 SAR1 表达增加。与 ARF1 转录物不同，ARF1 蛋白水平在根和茎组织的早期发育过程中没有明显波动。根组织中 SAR1 蛋白的相对丰度可能表明从内质网到高尔基体的囊泡运输水平较高。实验结果表明，白光可能影响 ARF1 和 SAR1 蛋白水平的调节。另一方面，短期的白光影响 SAR1，但不影响 ARF1。
