Distinct Rab27A binding affinities of Slp2-a and Slac2-a/melanophilin: Hierarchy of Rab27A effectors
Distinct Rab27A binding affinities of Slp2-a and Slac2-a/melanophilin: Hierarchy of Rab27A effectors
复制标题
DOI：
10.1016/j.bbrc.2006.03.001
复制
发表时间：
2006-05-05
影响因子：
3.1
通讯作者：
Fukuda, M
中科院分区：
文献类型：
--
作者：
Fukuda, M
最近已经显示小GTb 27 A通过与两个Rab 27 A效应物Slac 2-a/melanophilin和Slp 2-a顺序相互作用来调节哺乳动物皮肤黑素细胞中的黑素体转运。虽然Slac 2-a和Slp 2-a含有相似的N-末端Rab 27 A-结合结构域（命名为SHD，Slp同源结构域），但关于Slac 2-a SHD和Slp 2-a SHD之间的功能差异还不清楚。在这项研究中，Rab 27 A结合亲和力的10个推定Rab 27 A效应蛋白进行了研究。已经发现它们可以被分类为低亲和力组（例如，Slac 2-a）和高亲和力基团（例如，Slp 2-a和Slp 4-a）。通过表面等离子体共振对GTP-Rab 27 A与Slp 2-a、Slp 4-a和Slac 2-a的SHD结合的动力学分析进一步表明Rab 27 A对Slp 2-a SHD、Slp 4-a SHD和Slac 2-a SHD的动力学参数由快速结合速率常数组成（分别为3.35 x 10（4）、2.06 x 10（4）和2.11 x 10（4）M-1 s（-1））和缓慢解离速率常数（分别为4.48 × 10 ~（-4）、3.96 × 10 ~（-4）和2.37 × 10 ~（-3）s ~（-1）），它们的平衡解离常数分别为13.4、19.2、和112 nM。我们的数据表明，Slac 2-a和Slp 2-a的不同Rab 27 A结合活性确保Rab 27 A效应物在黑素细胞中的黑素体转运中顺序发挥作用的顺序（或层次）。(c)2006爱思唯尔公司All rights reserved.
The small GTPase Rab27A has recently been shown to regulate melanosome transport in mammalian skin melanocytes through sequentially interacting with two Rab27A effectors, Slac2-a/melanophilin and Slp2-a. Although Slac2-a and Slp2-a contain a similar N-terminal Rab27A-binding domain (named SHD, Slp homology domain), nothing is known about the functional differences between the Slac2-a SHD and Slp2-a SHD. In this study, the Rab27A-binding affinity of ten putative Rab27A effector proteins has been investigated. It has been found that they could be classified into a low-affinity group (e.g., Slac2-a) and a high-affinity group (e.g., Slp2-a and Slp4-a) based on their Rab27A-binding affinity. Kinetic analysis of the GTP-Rab27A-binding to the SHD of Slp2-a, Slp4-a, and Slac2-a by surface plasmon resonance further indicated that the kinetic parameters of Rab27A for the Slp2-a SHD, Slp4-a SHD, and Slac2-a SHD consisted of a fast association rate constant (3.35 x 10(4), 2.06 x 10(4), and 2.11 x 10(4) M-1 s(-1), respectively) and a slow dissociation rate constant (4.48 x 10(-4), 3.96 x 10(-4), and 2.37 x 10(-3) s(-1) respectively), and their equilibrium dissociation constants were determined to be 13.4, 19.2, and 112 nM, respectively. Our data suggest that distinct Rab27A binding activities of Slac2-a and Slp2-a ensure the order (or hierarchy) of Rab27A effectors that sequentially function in melanosome transport in melanocytes. (c) 2006 Elsevier Inc. All rights reserved.