Niinobe M, Yamaguchi Y, Fukuda M, Mikoshiba K
Institute for Protein Research, Osaka University, Japan.
Biochem Biophys Res Commun. 1994 Dec 15;205(2):1036-42. doi: 10.1006/bbrc.1994.2770.
We isolated a binding protein for inositol 1,3,4,5-tetrakisphosphate (InsP4) from detergent-solubilized mouse cerebellar membrane fractions by sequential column chromatographies. Partial amino acid sequencing of the purified sample revealed that the protein is essentially identical to rat synaptotagmin II, an integral membrane protein of synaptic vesicles. Immunoprecipitation experiment of [3H]InsP4 binding activity of the purified protein using polyclonal antibody against the C2A domain of rat synaptotagmin II also revealed that mouse synaptotagmin II is the InsP4 binding protein (IP4BP). Scatchard analysis of InsP4 binding to the IP4BP/synaptotagmin indicates a single binding site with a Kd of 30 nM. The present finding that InsP4 binds strongly to synaptotagmin II suggests an important role for inositol polyphosphates in the regulation of neurotransmitter release.
我们通过连续柱色谱法从去污剂溶解的小鼠小脑膜组分中分离出一种肌醇1,3,4,5 - 四磷酸（InsP4）结合蛋白。对纯化样品进行的部分氨基酸测序表明，该蛋白与大鼠突触结合蛋白II基本相同，后者是突触小泡的一种整合膜蛋白。使用针对大鼠突触结合蛋白II的C2A结构域的多克隆抗体对纯化蛋白的[3H]InsP4结合活性进行免疫沉淀实验，结果也表明小鼠突触结合蛋白II是InsP4结合蛋白（IP4BP）。对InsP4与IP4BP /突触结合蛋白结合的Scatchard分析表明存在一个Kd为30 nM的单一结合位点。InsP4与突触结合蛋白II强烈结合这一目前的发现表明肌醇多磷酸盐在神经递质释放调节中具有重要作用。
