Functional architecture of an intracellular membrane t-SNARE
Functional architecture of an intracellular membrane t-SNARE
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DOI：
10.1038/35025084
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发表时间：
2000-09-14
期刊：
影响因子：
64.8
通讯作者：
Söllner, TH
中科院分区：
文献类型：
--
作者：
Fukuda, R;McNew, JA;Söllner, TH
脂质双层融合由位于囊泡膜（v-SNARE）和靶膜（t-SNARE）上的SNARE（可溶性N-乙基-马来酰亚胺敏感因子附着蛋白受体）介导（1，2）。组装的v-SNARE/t-SNARE复合物由一束四个螺旋组成，其中一个由v-SNARE提供，另外三个由t-SNARE提供（3）。对于质膜上的t-SNARE，蛋白质突触融合蛋白（4）提供一个螺旋，SNAP-25蛋白（5）提供另外两个螺旋。虽然在细胞内膜上有许多突触融合蛋白的同源物（6），但在酵母中只有两种SNAP-25相关蛋白，Sec 9和Spo 20，两者都定位于质膜并分别在分泌（7）和孢子形成（8）中起作用。什么取代了细胞内膜t-SNARE中的SNAP-25？在这里，我们表明，细胞内的t-陷阱是建立从一个'重链'同源的syntaxin和两个独立的nonsyntaxin '轻链'。因此SNAP-25可能是例外而不是规则，它来源于编码单独轻链的基因，这些轻链在进化过程中融合产生编码一种具有两个螺旋的蛋白质的单一基因。
Lipid bilayer fusion is mediated by SNAREs (soluble N-ethyl-maleimide-sensitive factor attachment protein receptors) located on the vesicle membrane (v-SNAREs) and the target membrane (t-SNAREs)(1,2). The assembled v-SNARE/t-SNARE complex consists of a bundle of four helices, of which one is supplied by the v-SNARE and the other three by the t-SNARE(3). For t-SNAREs on the plasma membrane, the protein syntaxin(4) supplies one helix and a SNAP-25 protein(5) contributes the other two. Although there are numerous homologues of syntaxin on intracellular membranes(6), there are only two SNAP-25-related proteins in yeast, Sec9 and Spo20, both of which are localized to the plasma membrane and function in secretion(7) and sporulation(8), respectively. What replaces SNAP-25 in t-SNAREs of intracellular membranes? Here we show that an intracellular t-SNARE is built from a `heavy chain' homologous to syntaxin and two separate nonsyntaxin `light chains'. SNAP-25 may thus be the exception rather than the rule, having been derived from genes that encoded separate light chains that fused during evolution to produce a single gene encoding one protein with two helices.