PDF(Sci-hub)
Abstract：
Voltage-gated sodium channels (VGSCs) are fundamental to the initiation and propagation of action potentials in excitable cells. Ca2+/calmodulin (CaM) binds to VGSC type II (NaV1.2) isoleucine and glutamine (IQ) motif. An autism-associated mutation in NaV1.2 IQ motif, Arg1902Cys (R1902C), has been reported to affect the combination between CaM and the IQ motif compared to that of the wild type IQ motif. However, the detailed properties for the Ca2+-regulated binding of CaM to NaV1.2 IQ (1901Lys-1927Lys, IQwt) and mutant IQ motif (IQR1902C) remains unclear. Here, the binding ability of CaM and CaM\'s constituent proteins including N- and C lobe to the IQ motif of NaV1.2 and its mutant was investigated by protein pull-down experiments. We discovered that the combination between CaM and the IQ motif was U-shaped with the highest at [Ca2+] ≈ free and the lowest at 100 nM [Ca2+]. In the IQR1902C mutant, Ca2+-dependence of CaM binding was nearly lost. Consequently, the binding of CaM to IQR1902C at 100 and 500 nM [Ca2+] was increased compared to that of IQwt. Both N- and C lobe of CaM could bind with NaV1.2 IQ motif and IQR1902C mutant, with the major effect of C lobe. Furthermore, CaMKII had no impact on the binding between CaM and NaV1.2 IQ motif. This research offers novel insight to the regulation of NaV1.2 IQwt and IQR1902C motif, an autism-associated mutation, by CaM.
摘要：
电压门控钠通道（VGSC）对于可兴奋细胞中动作电位的启动和传播至关重要。Ca2/钙调蛋白（CaM）与VGSCII型（NaV1.2）异亮氨酸和谷氨酰胺（IQ）基序结合。NaV1.2智商基序中的自闭症相关突变，Arg1902Cys(R1902C),据报道，与野生型IQ基序相比，CaM和IQ基序之间的组合会受到影响。然而,CaM与NaV1.2IQ（1901Lys-1927Lys，IQwt）和突变体IQ基序（IQR1902C）仍不清楚。这里,通过蛋白质下拉实验研究了CaM和CaM的组成蛋白包括N和C叶与NaV1.2及其突变体的IQ基序的结合能力。我们发现CaM和IQ基序之间的组合是U形的，在[Ca2]≈游离时最高，在100nM[Ca2]时最低。在IQR1902C突变体中，CaM结合的Ca2依赖性几乎丧失。因此,与IQwt相比，CaM与100和500nM[Ca2]的IQR1902C的结合增加。CaM的N叶和C叶都可以与NaV1.2IQ基序和IQR1902C突变体结合，C叶的主要作用。此外，CaMKII对CaM和NaV1.2IQ基序之间的结合没有影响。这项研究为NaV1.2IQwt和IQR1902C基序的调节提供了新的见解，自闭症相关的突变，由CaM
