Two syntaxin homologues in the TGN/endosomal system of yeast
Two syntaxin homologues in the TGN/endosomal system of yeast
复制标题
DOI：
10.1093/emboj/17.1.113
复制
发表时间：
1998-01-02
期刊：
影响因子：
11.4
通讯作者：
Pelham, HRB
中科院分区：
文献类型：
--
作者：
Holthuis, JCM;Nichols, BJ;Pelham, HRB
细胞内的膜运输被认为是部分由SNARE调节的，SNARE是运输囊泡上的膜蛋白（v-SNARE）和靶细胞器所有已知的SNARE介导的融合事件都涉及t-SNARE的突触融合蛋白家族的成员。序列比较鉴定了在酵母基因组中编码的八种这样的蛋白质，其中六种已经被表征，我们在这里描述了剩下的两个，Tlg 1 p和Tlg 2 p，它们具有t-SNARE的预期生化特性，并且位于可分离的隔室中，分别对应于推定的早期内体和TGN的酵母等同物，它们与v-SNARE Vti 1 p共沉淀，Vti 1 p涉及高尔基体-内体运输，并且显著地结合五种不同的突触融合蛋白，Tlg 1 p也结合质膜v-SNARE Snc 1 p，Tlg 1 p和Tlg 2 p都是有效的内吞作用和维持正常水平的TGN蛋白所必需的，然而，两者都不是高尔基体内运输所必需的，因为在酵母中没有进一步的突触融合蛋白被鉴定，这意味着高尔基体可以与单个突触融合蛋白Sed 5 p一起起作用。
Intracellular membrane traffic is thought to be regulated in part by SNAREs, integral membrane proteins on transport vesicles (v-SNAREs) and target organelles (t-SNAREs) that bind to each other and mediate bilayer fusion, All known SNARE-mediated fusion events involve a member of the syntaxin family of t-SNAREs, Sequence comparisons identify eight such proteins encoded in the yeast genome, of which six have been characterized, We describe here the remaining two, Tlg1p and Tlg2p, These have the expected biochemical properties of t-SNAREs, and are located in separable compartments which correspond to a putative early endosome and the yeast equivalent of the TGN, respectively They co-precipitate with the v-SNARE Vti1p, which is implicated in Golgi-endosome traffic and, remarkably, binds to five different syntaxins, Tlg1p also binds the plasma membrane v-SNARE Snc1p, Both Tlg1p and Tlg2p are required for efficient endocytosis and to maintain normal levels of TGN proteins, However, neither is required for intra-Golgi traffic, Since no further syntaxins have been identified in yeast, this implies that the Golgi apparatus can function with a single syntaxin, Sed5p.