Chu Po-Ju, Rivera Jacqueline F, Arnold Don B
Department of Biology and Program in Molecular and Computational Biology, University of Southern California, Los Angeles, California 90089-2910, USA.
J Biol Chem. 2006 Jan 6;281(1):365-73. doi: 10.1074/jbc.M508897200. Epub 2005 Oct 28.
Although kinesins are known to transport neuronal proteins, it is not known what role they play in the targeting of their cargos to specific subcellular compartments in neurons. Here we present evidence that the K+ channel Kv4.2, which is a major regulator of dendritic excitability, is transported to dendrites by the kinesin isoform Kif17. We show that a dominant negative construct against Kif17 dramatically inhibits localization to dendrites of both introduced and endogenous Kv4.2, but those against other kinesins found in dendrites do not. Kv4.2 colocalizes with Kif17 but not with other kinesin isoforms in dendrites of cortical neurons. Native Kv4.2 and Kif17 coimmunoprecipitate from brain lysate, and introduced, tagged versions of the two proteins coimmunoprecipitate from COS cell lysate, indicating that the two proteins interact, either directly or indirectly. The interaction between Kif17 and Kv4.2 appears to occur through the extreme C terminus of Kv4.2 and not through the dileucine motif. Thus, the dileucine motif does not determine the localization of Kv4.2 by causing the channel to interact with a specific motor protein. In support of this conclusion, we found that the dileucine motif mediates dendritic targeting of CD8 independent of Kif17. Together our data show that Kif17 is probably the motor that transports Kv4.2 to dendrites but suggest that this motor does not, by itself, specify dendritic localization of the channel.
尽管已知驱动蛋白可运输神经元蛋白，但它们在将其货物靶向神经元中的特定亚细胞区室时发挥何种作用尚不清楚。在此，我们提供证据表明，作为树突兴奋性主要调节因子的钾离子通道Kv4.2，由驱动蛋白异构体Kif17运输至树突。我们发现，针对Kif17的显性负性构建体显著抑制了导入的和内源性Kv4.2向树突的定位，但针对树突中发现的其他驱动蛋白的构建体则没有这种作用。在皮质神经元的树突中，Kv4.2与Kif17共定位，但不与其他驱动蛋白异构体共定位。天然的Kv4.2和Kif17可从脑裂解物中共免疫沉淀，并且导入的、带有标签的这两种蛋白版本可从COS细胞裂解物中共免疫沉淀，这表明这两种蛋白直接或间接相互作用。Kif17与Kv4.2之间的相互作用似乎是通过Kv4.2的极端C末端发生的，而不是通过双亮氨酸基序。因此，双亮氨酸基序并非通过使通道与特定的驱动蛋白相互作用来决定Kv4.2的定位。为支持这一结论，我们发现双亮氨酸基序介导CD8的树突靶向，且不依赖于Kif17。我们的数据共同表明，Kif17可能是将Kv4.2运输至树突的驱动蛋白，但表明该驱动蛋白本身并不能指定通道的树突定位。
