Institute of Biology II/Molecular Plant Physiology, Faculty of Biology, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.
Plant Signal Behav. 2012 Nov;7(11):1504-5. doi: 10.4161/psb.21953. Epub 2012 Sep 18.
Cellular auxin homeostasis is controlled at many levels that include auxin biosynthesis, auxin metabolism, and auxin transport. In addition to intercellular auxin transport, auxin homeostasis is modulated by auxin flow through the endoplasmic reticulum (ER). PIN5, a member of the auxin efflux facilitators PIN protein family, was the first protein to be characterized as an intracellular auxin transporter. We demonstrated that PIN8, the closest member of the PIN family to PIN5, represents another ER-residing auxin transporter. PIN8 is specifically expressed in the male gametophyte and is located in the ER. By combining genetic, physiological, cellular and biochemical data we demonstrated a role for PIN8 in intracellular auxin homeostasis. Although our investigation shed light on intracellular auxin transport in pollen, the physiological function of PIN8 still remains to be elucidated. Here we discuss our data taking in consideration other recent findings.
细胞生长素稳态在许多层面上受到控制，包括生长素的生物合成、代谢和运输。除了细胞间生长素运输外，生长素稳态还通过内质网 (ER) 中的生长素流动来调节。PIN5 是生长素外排促进因子 PIN 蛋白家族的成员之一，它是第一个被表征为细胞内生长素转运体的蛋白质。我们证明，PIN 家族中与 PIN5 最接近的成员 PIN8 代表了另一种驻留在内质网中的生长素转运体。PIN8 特异性表达在雄性配子体中，并位于内质网中。通过结合遗传、生理、细胞和生化数据，我们证明了 PIN8 在细胞内生长素稳态中的作用。尽管我们的研究揭示了花粉中细胞内生长素运输的情况，但 PIN8 的生理功能仍有待阐明。在这里，我们结合其他最近的发现讨论我们的数据。
