LMA1与Sec18p（NSF）处的液泡结合，在ATP水解后转移至t-SNARE（Vam3p）复合体，并在融合过程中释放。

LMA1 binds to vacuoles at Sec18p (NSF), transfers upon ATP hydrolysis to a t-SNARE (Vam3p) complex, and is released during fusion.

作者信息

Xu Z, Sato K, Wickner W

机构信息

Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.

出版信息

Cell. 1998 Jun 26;93(7):1125-34. doi: 10.1016/s0092-8674(00)81457-9.

DOI:10.1016/s0092-8674(00)81457-9

PMID:9657146

Abstract

Vacuole fusion requires Sec18p (NSF), Sec17p (alpha-SNAP), Ypt7p (GTP binding protein), Vam3p (t-SNARE), Nyv1p (v-SNARE), and LMA1 (low Mr activity 1, a heterodimer of thioredoxin and I(B)2). LMA1 requires Sec18p for saturable, high-affinity binding to vacuoles, and Sec18p "priming" ATPase requires both Sec17p and LMA1. Either the sec18-1 mutation and deletion of I(B)2, or deletion of both I(B)2 and p13 (an I(B)2 homolog) causes a striking synthetic vacuole fragmentation phenotype. Upon Sec18p ATP hydrolysis, LMA1 transfers to (and stabilizes) a Vam3p complex. LMA1 is released from vacuoles in a phosphatase-regulated reaction. This LMA1 cycle explains how priming by Sec18p is coupled to t-SNARE stabilization and to fusion.

摘要

液泡融合需要Sec18p（N-乙基马来酰胺敏感因子，NSF）、Sec17p（α-可溶性NSF附着蛋白，α-SNAP）、Ypt7p（GTP结合蛋白）、Vam3p（靶膜可溶性NSF附着蛋白受体，t-SNARE）、Nyv1p（囊泡膜可溶性NSF附着蛋白受体，v-SNARE）和LMA1（低分子量活性蛋白1，一种由硫氧还蛋白和I(B)2组成的异二聚体）。LMA1需要Sec18p才能以可饱和的高亲和力与液泡结合，并且Sec18p“引发”ATP酶需要Sec17p和LMA1两者。sec18-1突变和I(B)2的缺失，或者I(B)2和p13（一种I(B)2同源物）两者的缺失都会导致明显的合成液泡碎片化表型。在Sec18p进行ATP水解时，LMA1转移至（并稳定）Vam3p复合物。LMA1在磷酸酶调节的反应中从液泡中释放。这个LMA1循环解释了Sec18p引发如何与t-SNARE稳定化以及融合相偶联。