Promiscuity in Rab-SNARE interactions
Promiscuity in Rab-SNARE interactions
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DOI：
10.1091/mbc.10.12.4149
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发表时间：
1999-12-01
影响因子：
3.3
通讯作者：
Novick, PJ
中科院分区：
文献类型：
--
作者：
Grote, E;Novick, PJ
后高尔基体分泌囊泡与酵母质膜的融合需要以下蛋白的功能：Rab蛋白，Sec 4p，和一组v-和t-SNARE，Snc，Sso和Sec 9蛋白。我们已经测试了假设Sec 4p和胞外SNARE之间的选择性相互作用是负责确保分泌囊泡与质膜融合，但不与细胞内细胞器。在sec 4 -8突变株中，Sncp和Ssop组装成SNARE复合物是有缺陷的。然而，Snc 2 p在体内与许多其他突触融合蛋白样t-SNARE结合，并且Sncp与内体/高尔基体t-SNARE Tlg 2 p的结合在sec 4 -8细胞中也减少。此外，Sncp与Ssop的结合被另外两个Rab基因和四个非Rab基因中的突变减少，所述突变在分泌囊泡形成之前阻断分泌途径。在另一种寻找选择性Rab-SNARE相互作用的方法中，我们报告了Sec 4p的无核苷酸形式与Ssop共免疫沉淀。然而，Rab-SNARE结合是非选择性的，因为六种Rab蛋白的无核苷酸形式以类似的低效率结合三种SNARE蛋白，Ssop，Pep 12 p和Sncp。我们的结论是，Rabs和SNARE不合作，以指定的目标膜。
Fusion of post-Golgi secretory vesicles with the plasma membrane in yeast requires the function of:a Rab protein, Sec4p, and a set of v- and t-SNAREs, the Snc, Sso, and Sec9 proteins. We have tested the hypothesis that a selective interaction between Sec4p and the exocytic SNAREs is responsible for ensuring that secretory vesicles fuse with the plasma membrane but not with intracellular organelles. Assembly of Sncp and Ssop into a SNARE complex is defective in a sec4-8 mutant strain. However, Snc2p binds in vivo to-many other syntaxin-like t-SNAREs, and binding of Sncp to the endosomal/Golgi t-SNARE Tlg2p is also reduced in sec4-8 cells. In addition, binding of Sncp to Ssop is reduced by mutations in two other Rab genes and four non-Rab genes that block the secretory pathway before the formation of secretory vesicles. Ln an alternate approach to look for selective Rab-SNARE interactions, we report that the nucleotide-free form of Sec4p coimmunoprecipitates with Ssop. However, Rab-SNARE binding is nonselective, because the nucleotide-free forms of six Rab proteins bind with similar low efficiency to three SNARE proteins, Ssop, Pep12p, and Sncp. We conclude that Rabs and SNAREs do not cooperate to specify the target membrane.