SPECIFIC INTERACTIONS OF MSS4 WITH MEMBERS OF THE RAB GTPASE SUBFAMILY
SPECIFIC INTERACTIONS OF MSS4 WITH MEMBERS OF THE RAB GTPASE SUBFAMILY
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DOI：
10.1002/j.1460-2075.1994.tb06892.x
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发表时间：
1994-12-01
期刊：
影响因子：
11.4
通讯作者：
DECAMILLI, P
中科院分区：
文献类型：
--
作者：
BURTON, JL;BURNS, ME;DECAMILLI, P
Mss4是一种哺乳动物蛋白，被鉴定为含有GTPase Sec4突变的酵母分泌突变体的抑制物，并被发现能刺激该蛋白释放GDP。我们现在对Mss4蛋白进行了生化特征分析，并研究了其与哺乳动物GTP酶的相关性。Mss4主要是一种组织分布广泛的可溶性蛋白。重组Mss4结合存在于组织提取液中的GTP酶，并通过凝胶覆盖实验特异性地结合Rab Rab10蛋白。我们进一步将Mss4-GTPase相互作用定义为属于同一亚家族分支的RAB的一个子集，包括Rab1、Rab3、Rab8、Rab10、Sec4和Ypt1，但不包括Rab2、Rab4、Rab5、Rab6、Rab9和Rab11。因此，Mss 4与Rab3a而不是Rab5从脑提取物中共沉淀出来，Mss 4只刺激GDP的释放，GTP Gamma S与这个Rab亚集、重组Mss 4和Rab3a在溶液中形成一个稳定的复合体，它与GDP或GTP Gamma S解离。将Mss 4注射到鱿鱼巨大神经末梢可以促进神经递质的释放。这些结果表明，Mss4作为一种鸟苷核苷酸交换因子，作用于RABS的一部分，从而影响沿着分泌途径的不同的囊泡运输步骤。
Mss4 is a mammalian protein that was identified as a suppressor of a yeast secretory mutant harboring a mutation in the GTPase Sec4 and was found to stimulate GDP release from this protein, We have now performed a biochemical characterization of the Mss4 protein and examined the specificity of its association with mammalian GTPases. Mss4 is primarily a soluble protein with a widespread tissue distribution. Recombinant Mss4 binds GTPases present in tissue extracts, and by a gel overlay assay binds specifically Rab Rab10proteins. We further define the Mss4-GTPase interaction to a subset of Rabs belonging to the same subfamily branch which include Rab1, Rab3, Rab8, Rab10, Sec4 and Ypt1 but not Rab2, Rab4, Rab5, Rab6, Rab9 and Rab11. Accordingly, Mss4 co-precipitates from a brain extract with Rab3a but not Rab5, Mss4 only stimulates GDP release from, and the association of GTP gamma S with, this Rab subset, Recombinant Mss4 and Rab3a form a stable complex in solution that is dissociated with either GDP or GTP gamma S. Injection of Mss4 into the squid giant nerve terminal enhances neurotransmitter release. These results suggest that Mss4 behaves as a guanylnucleotide exchange factor (GEF) for a subset of Rabs to influence distinct vesicular transport steps along the secretory pathway.