Regulation of Exocytosis through Ca2+/ATP-Dependent Binding of Autophosphorylated Ca2+/Calmodulin-Activated Protein Kinase II to Syntaxin 1A
Regulation of Exocytosis through Ca2+/ATP-Dependent Binding of Autophosphorylated Ca2+/Calmodulin-Activated Protein Kinase II to Syntaxin 1A
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DOI：
10.1523/jneurosci.22-09-03342.2002
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发表时间：
2002-05
期刊：
影响因子：
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通讯作者：
A. Ohyama;K. Hosaka;Y. Komiya;K. Akagawa;E. Yamauchi;H. Taniguchi;Nobuyuki Sasagawa;K. Kumakura;S. Mochida;T. Yamauchi;M. Igarashi
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文献类型：
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作者：
A. Ohyama;K. Hosaka;Y. Komiya;K. Akagawa;E. Yamauchi;H. Taniguchi;Nobuyuki Sasagawa;K. Kumakura;S. Mochida;T. Yamauchi;M. Igarashi
Synaxin 1A/HPC-1是胞吐分子机制的关键组成部分，即可溶性N-乙基马来酰亚胺敏感因子附着蛋白(SNAP)受体机制。尽管>；10合成素结合蛋白已被鉴定，但它们不能完全解释胞吐作用的调节。因此，新的蛋白质可能与合成素相互作用。由于胞吐作用既需要钙离子又需要三磷酸腺苷，我们从大鼠脑中寻找钙/三磷酸腺苷依赖的合成素结合蛋白，发现了钙/钙调蛋白激活蛋白激酶II(CaMKII)-α。在Ca~(2+)浓度为>；10−6M时，只有自磷酸化的CaMKⅡ能与突触素结合。结合的CaMKII可被EGTA或磷酸酶从Synaxin中释放，表明结合是可逆的。CaMKII结合到合成素的连接器域，不像任何其他已知的合成素结合蛋白。免疫沉淀法也在突触体中检测到CaMKII-Synaxin复合体，在体外重组时，它们招募到的突触凝集素和SNAP-25比单独的Synaxin更多。显微注射的CaMKII结合域的Synaxin特异性地影响嗜铬细胞和神经元的胞吐。这些结果表明，CaMKII依赖于Ca~(2+)/ATP的结合是胞吐过程中的重要过程。
Syntaxin 1A/HPC-1 is a key component of the exocytotic molecular machinery, namely, the solubleN-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor mechanism. Although >10 syntaxin-binding proteins have been identified, they cannot completely explain the regulation of exocytosis. Thus, novel proteins may interact with syntaxin. Because exocytosis requires both Ca2+ and ATP, we searched for Ca2+/ATP-dependent syntaxin-binding proteins from the rat brain and discovered Ca2+/calmodulin-activated protein kinase II (CaMKII)-α. At Ca2+ concentrations of >10−6m, only autophosphorylated CaMKII bound to syntaxin. Bound CaMKII was released from syntaxin by EGTA or by phosphatase, indicating that the binding is reversible. CaMKII bound to the linker domain of syntaxin, unlike any other known syntaxin-binding proteins. CaMKII–syntaxin complexes were also detected in synaptosomes by immunoprecipitation, and when reconstitutedin vitro, they recruited larger amounts of synaptotagmin and SNAP-25 than syntaxin alone. The microinjected CaMKII-binding domain of syntaxin specifically affected exocytosis in chromaffin cells and in neurons. These results indicate that the Ca2+/ATP-dependent binding of CaMKII to syntaxin is an important process in the regulation of exocytosis.