CAST2: identification and characterization of a protein structurally related to the presynaptic cytomatrix protein CAST
CAST2: identification and characterization of a protein structurally related to the presynaptic cytomatrix protein CAST
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DOI：
10.1111/j.1356-9597.2004.00697.x
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发表时间：
2004-01-01
期刊：
影响因子：
2.1
通讯作者：
Takai, Y
中科院分区：
文献类型：
--
作者：
Deguchi-Tawarada, M;Inoue, E;Takai, Y
活动区（CAZ）的细胞基质被认为是确定神经递质的Ca 2+依赖性胞吐的位点。我们最近从大鼠脑中发现了一种新的CAZ蛋白，我们将其命名为CAST（CAZ相关结构蛋白）。CAST与其他CAZ蛋白如Bassoon，RIM1和Munc13 - 1形成大分子复合物，至少通过与RIM1直接结合。在这里，我们已经确定了一种与CAST结构相关的大鼠蛋白质，并将其命名为CAST 2。大鼠脑的亚细胞分级分析表明，CAST 2也与突触后密度分数密切相关。与CAST一样，CAST 2直接结合RIM 1并与CAST形成异源寡聚体。在原代培养的大鼠海马神经元中，CAST 2与巴松管共定位于突触。此外，免疫电镜显示，CAST 2定位于小鼠脑突触的突触前膜附近。序列分析表明，CAST 2是人类蛋白ELKS的大鼠直向同源物。ELKS最近也被确定为Rab6IP2和ERC1。因此，最初的CAST暂时被重新命名为CAST 1。这些结果表明，CAST 2是CAZ的一个新的组成部分，并与CAST 1，可能参与了CAZ结构的形成。
The cytomatrix at the active zone (CAZ) is thought to define the site of Ca2+-dependent exocytosis of neurotransmitters. We have recently identified a novel CAZ protein from rat brain which we have named CAST (CAZ-associated structural protein). CAST forms a large molecular complex with other CAZ proteins such as Bassoon, RIM1 and Munc13-1, at least through direct binding to RIM1. Here, we have identified a rat protein that is structurally related to CAST and named it CAST2. Subcellular fractionation analysis of rat brain shows that CAST2 is also tightly associated with the postsynaptic density fraction. Like CAST, CAST2 directly binds RIM1 and forms a hetero-oligomer with CAST. In primary cultured rat hippocampal neurones, CAST2 co-localizes with Bassoon at synapses. Furthermore, immunoelectron microscopy reveals that CAST2 localizes to the vicinity of the presynaptic membrane of synapses in mouse brain. Sequence analysis reveals that CAST2 is a rat orthologue of the human protein ELKS. ELKS has also recently been identified as Rab6IP2 and ERC1. Accordingly, the original CAST is tentatively re-named CAST1. These results indicate that CAST2 is a new component of the CAZ and, together with CAST1, may be involved in the formation of the CAZ structure.