Muschietti J, Eyal Y, McCormick S
Plant Gene Expression Center, U.S. Department of Agriculture-Agricultural Research Service, and University of California at Berkeley, 800 Buchanan Street, Albany, California 94710, USA.
Plant Cell. 1998 Mar;10(3):319-30. doi: 10.1105/tpc.10.3.319.
We screened for pollen-specific kinase genes, which are potential signal transduction components of pollen-pistil interactions, and isolated two structurally related receptor-like kinases (RLKs) from tomato, LePRK1 and LePRK2. These kinases are similar to a pollen-expressed RLK from petunia, but they are expressed later during pollen development than is the petunia RLK. The abundance of LePRK2 increases when pollen germinates, but LePRK1 remains constant. Both LePRK1 and LePRK2 are localized to the plasma membrane/cell wall of growing pollen tubes. Both kinase domains have kinase activity when expressed in Escherichia coli. In phosphorylation assays with pollen membrane preparations, LePRK2, but not LePRK1, is phosphorylated, and the addition of tomato style, but not leaf, extracts to these membrane preparations results at least partially in specific dephosphorylation of LePRK2. Taken together, these results suggest that LePRK1 and LePRK2 play different roles in postpollination events and that at least LePRK2 may mediate some pistil response.
我们筛选了花粉特异性激酶基因，这些基因是花粉与雌蕊相互作用中潜在的信号转导成分，并从番茄中分离出两个结构相关的类受体激酶（RLK），即LePRK1和LePRK2。这些激酶与矮牵牛中一个花粉表达的RLK相似，但它们在花粉发育过程中的表达时间比矮牵牛RLK晚。花粉萌发时LePRK2的丰度增加，但LePRK1保持恒定。LePRK1和LePRK2都定位于生长中的花粉管的质膜/细胞壁。当在大肠杆菌中表达时，两个激酶结构域都具有激酶活性。在用花粉膜制剂进行的磷酸化测定中，LePRK2被磷酸化，而LePRK1未被磷酸化，并且向这些膜制剂中添加番茄花柱提取物而非叶片提取物至少部分导致LePRK2的特异性去磷酸化。综上所述，这些结果表明LePRK1和LePRK2在授粉后事件中发挥不同作用，并且至少LePRK2可能介导一些雌蕊反应。
