Department of Biology, University of North Carolina, Chapel Hill, NC, USA.
Plant Signal Behav. 2010 Jul;5(7):896-8. doi: 10.4161/psb.5.7.12094. Epub 2010 Jul 1.
Cytokinins are a class of mitogenic plant hormones that influence shoot and root growth, vascular and photomorphogenic development, leaf senescence, and many other aspects of plant growth and development. The Arabidopsis histidine phosphotransfer proteins (AHPs) play an important role in cytokinin signaling by bridging the perception of cytokinins by plasma-membrane receptors to the activation of cytokinin-responsive transcription factors. Based on previous microscopic observations, a model was developed in which the AHPs were thought to relocalize from the cytosol into the nucleus in response to exogenous cytokinin. However, analysis and quantification of the intracellular distribution of AHPs in both protoplasts and intact transgenic plants revealed that the subcellular localization of the AHPs is persistently nucleo-cytosolic and non-responsive to the state of the cytokinin response pathway. Here, we review and extend these findings and discuss their implications.
细胞分裂素是一类具有丝裂原活性的植物激素，影响芽和根的生长、维管和光形态建成发育、叶片衰老以及植物生长和发育的许多其他方面。拟南芥组氨酸磷酸转移蛋白（AHPs）通过将细胞分裂素的感知与细胞分裂素响应转录因子的激活联系起来，在细胞分裂素信号转导中发挥重要作用。基于先前的显微镜观察结果，提出了一个模型，即 AHPs 被认为在外源细胞分裂素的作用下从细胞质重新定位到细胞核。然而，对原生质体和完整转基因植物中 AHPs 细胞内分布的分析和定量表明，AHPs 的亚细胞定位持续为核质，并对细胞分裂素反应途径的状态无反应。在这里，我们回顾和扩展了这些发现，并讨论了它们的意义。
