The ciliate Paramecium tetraurelia has four arginine kinase genes (AK1, AK2, AK3, and AK4). Of these genes, only AK3 has a signal sequence for farnesylation, a post-translational modification that enables anchoring of the modified enzyme to the ciliary membrane. To confirm this modification, AK3 was synthesized using a cell-free protein synthesis system and the peptide masses were analyzed using peptide mass fingerprinting (PMF). The PMF analysis indicated that the C-terminal peptide of AK3 is farnesylated. Thus, AK3 can be farnesylated under physiologically appropriate conditions. To determine the subcellular localization of P. tetraurelia AK3, Western blot analysis was performed using an AK3 polyclonal antibody for the proteins extracted from intact cells and ciliary fractions. When extraction was performed using Triton X-100, AK3 was detected the ciliary fraction. This result suggested that the ciliary fraction contains AK3. In addition, we investigated the role of P. tetraurelia AKs in ciliary movement using the feeding RNA interference method. The swimming velocity of AK1- and AK3-silenced cells was significantly reduced to half the value of that control cells. In summary, P. tetraurelia AK3 is likely to be located in the ciliary membrane and influences swimming velocity, presumably through the phosphoarginine shuttle system present in cilia.

纤毛虫草履虫具有四个精氨酸激酶基因（AK1，AK2，AK3和AK4）。在这些基因中，只有AK3具有法尼基化的信号序列，法尼基化是一种翻译后修饰，可将修饰的酶锚定在睫状膜上。为了证实该修饰，使用无细胞蛋白质合成系统合成了AK3，并使用肽质量指纹图谱（PMF）分析了肽质量。PMF分析表明，AK3的C端肽被法尼基化。因此，可以在生理上合适的条件下对AK3进行法呢基化。为了确定四尿假单胞菌的亚细胞定位AK3，使用AK3多克隆抗体对从完整细胞和睫状级分中提取的蛋白质进行蛋白质印迹分析。当使用Triton X-100进行提取时，检测到AK3的睫状级分。该结果表明睫状级分含有AK3。此外，我们使用饲喂RNA干扰方法研究了四脲假单胞菌AK在睫状运动中的作用。沉默AK1和AK3的细胞的游泳速度显着降低到该对照细胞的一半。总之，P. tetraurelia AK3很可能被定位于睫状膜和影响游泳速度，推测是通过存在于纤毛phosphoarginine穿梭系统。