Max Planck Institute of Molecular Physiology, Structural Biology Department, Otto Hahn Strasse 11, 44227 Dortmund, Germany.
Eur J Cell Biol. 2010 Dec;89(12):917-23. doi: 10.1016/j.ejcb.2010.08.002. Epub 2010 Sep 15.
The pollen-specific receptor-like kinases (PRKs) from Solanum lycopersicum, LePRK1 and LePRK2, are believed to be involved in the regulation of pollen germination and pollen tube growth. They appear to be part of a multimeric complex in which the transmembranic LePRKs presumably have a key position in transducing exogenous signals through the plasma membrane. Here, we focused on extra- and intracellular interactions involving the LePRKs. We show in yeast two-hybrid experiments a cross-interaction of putative PRK-ligands, the oligomerization of LePRK2 and a direct contact of LePRKs to activated Rho proteins of plants (ROPs). Moreover, we observed that pollen-specific RopGEFs, which catalyze ROP activation and may be regulated by PRK interaction, are active in vitro while autoinhibition seems to occur in vivo. We suggest that activation of RopGEFs as a checkpoint in PRK signal transduction is a more complex event including further components in planta. Our findings point to some new aspects in PRK-mediated signal transduction implying a LePRK2 complex with different signaling activity and a further direct control of LePRKs by activated ROP.
番茄花粉特异受体样激酶（PRKs）LePRK1 和 LePRK2 可能参与调控花粉萌发和花粉管生长。它们似乎是多聚体复合物的一部分，其中跨膜 LePRKs 很可能在通过质膜转导外源性信号中起关键作用。在这里，我们重点研究了涉及 LePRKs 的细胞外和细胞内相互作用。我们在酵母双杂交实验中证明了假定的 PRK 配体之间的交叉相互作用，LePRK2 的寡聚化以及 LePRKs 与植物激活的 Rho 蛋白（ROPs）的直接接触。此外，我们观察到，催化 ROP 激活并可能受 PRK 相互作用调控的花粉特异 RopGEFs 在体外具有活性，而自身抑制似乎发生在体内。我们认为，作为 PRK 信号转导中的检查点，ROPGEFs 的激活是一个更复杂的事件，包括植物体内的其他成分。我们的研究结果表明，PRK 介导的信号转导存在一些新的方面，暗示 LePRK2 复合物具有不同的信号活性，以及激活的 ROP 对 LePRKs 的进一步直接控制。
