Slac2-a/melanophilin, the missing link between Rab27 and myosin Va - Implications of a tripartite protein complex for melanosome transport
Slac2-a/melanophilin, the missing link between Rab27 and myosin Va - Implications of a tripartite protein complex for melanosome transport
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DOI：
10.1074/jbc.c200005200
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发表时间：
2002-04-05
影响因子：
4.8
通讯作者：
Mikoshiba, K
中科院分区：
文献类型：
--
作者：
Fukuda, M;Kuroda, TS;Mikoshiba, K
肌球蛋白Va是非常规V类肌球蛋白家族的成员，肌球蛋白Va基因的突变会导致人类Griscelli综合征和稀释小鼠的色素颗粒转运缺陷。然而，在过去的十年里，肌球蛋白Va如何识别其货物（即黑素体）仍然没有确定。在这项研究中，我们发现Slac 2-a/melanophilin是黑素体中肌球蛋白Va和GTP-Rab 27 A之间的“缺失环节”。缺失分析和定点突变显示Slac 2-a的N-末端Slp（突触结合蛋白样蛋白）同源结构域特异性结合Rab 27 A/B同种型，并且C-末端的一半直接结合肌球蛋白Va的球状尾。三重蛋白复合物（Rab 27 A（.）Slac 2-a（.）肌球蛋白Va）在黑色素瘤细胞中的表达进一步通过免疫沉淀证实。肌球蛋白Va通过一种新的Rab 27 A/B效应子Slac 2-a间接识别其货物的发现，应该阐明V类肌球蛋白对其特异性货物的分子识别。
Myosin Va is a member of the unconventional class V myosin family, and a mutation in the myosin Va gene causes pigment granule transport defects in human Griscelli syndrome and dilute mice. How myosin Va recognizes its cargo (i.e. melanosomes), however, has remained undetermined over the past decade. In this study, we discovered Slac2-a/melanophilin to be the "missing link" between myosin Va and GTP-Rab27A present in the melanosome. Deletion analysis and site-directed mutagenesis showed that the N-terminal Slp (synaptotagmin-like protein) homology domain of Slac2-a specifically binds Rab27A/B isoforms and that the C-terminal half directly binds the globular tail of myosin Va. The tripartite protein complex (Rab27A(.)Slac2-a(.)myosin Va) in melanoma cells was further confirmed by immunoprecipitation. The discovery that myosin Va indirectly recognizes its cargo through Slac2-a, a novel Rab27A/B effector, should shed light on molecular recognition of its specific cargo by class V myosin.