Kühn Frank J P, Kühn Cornelia, Naziroglu Mustafa, Lückhoff Andreas
Institute of Physiology, Medical Faculty, RWTH Aachen, 52057, Aachen, Germany.
Neurochem Res. 2009 Feb;34(2):227-33. doi: 10.1007/s11064-008-9755-0. Epub 2008 Jun 3.
In the dysfunctional splice variant TRPM2-DeltaN, a stretch of 20 amino acids (aa 537-556) is missing within the N-terminal cytosolic tail of the cation channel TRPM2. The DeltaN-stretch overlaps with two IQ-like calmodulin-binding domains. Moreover, it contains two PxxP motifs implicated in protein-protein interactions. Here, we constructed variants to test whether any of these motifs may explain why TRPM2-DeltaN does not respond to stimulation with either ADP ribose or hydrogen peroxide. Each of the two IQ-motifs could be removed without loss of channel function. Similarly, deletion of either one or both PxxP motifs had no effect. Moreover, the single point mutation D543E associated with bipolar disorder does not change the activation of TRPM2. We conclude that no functional role can be attributed to any of the structural motifs within the DeltaN-stretch that may be a spacer segment for other functional sites in the N terminus.
在功能失调的剪接变体TRPM2-DeltaN中，阳离子通道TRPM2的N端胞质尾部缺失一段20个氨基酸（第537-556位氨基酸）。DeltaN片段与两个类IQ钙调蛋白结合结构域重叠。此外，它包含两个与蛋白质-蛋白质相互作用有关的PxxP基序。在此，我们构建了变体，以测试这些基序中的任何一个是否可以解释为什么TRPM2-DeltaN对ADP核糖或过氧化氢的刺激没有反应。两个IQ基序中的任何一个都可以去除而不丧失通道功能。同样，删除一个或两个PxxP基序也没有影响。此外，与双相情感障碍相关的单点突变D543E不会改变TRPM2的激活。我们得出结论，DeltaN片段内的任何结构基序都没有功能作用，该片段可能是N端其他功能位点的间隔区段。
