Liu Y, Fisher D A, Storm D R
Department of Pharmacology, University of Washington School of Medicine, Seattle 98195.
J Neurosci. 1994 Oct;14(10):5807-17. doi: 10.1523/JNEUROSCI.14-10-05807.1994.
Neuromodulin (GAP-43) is a neurospecific calmodulin binding protein that is targeted to neuronal growth cones via fast axonal transport by an undefined mechanism. The protein is associated with membranes by palmitoylation of cys-3 and cys-4. The objective of this study was to examine the intracellular localization of neuromodulin and neuromodulin mutants modified in the membrane targeting domain of the protein in neurons and non-neuronal cells. The N-terminal palmitoylation domain of neuromodulin was found to be sufficient for membrane and Golgi targeting as well as neurite transport. A fusion protein consisting of the N-terminal 20 amino acids of neuromodulin and beta-galactosidase accumulated in neurite endings demonstrating that this sequence is sufficient for targeting to growth cone membranes. Mutations in the palmitoylation domain of neuromodulin that abolished its acylation and membrane association diminished its Golgi localization. Mutations that prevented Golgi accumulation of neuromodulin-beta-galactosidase fusion proteins also interfered with neurite transport of the fusion proteins. These data demonstrate a correlation between membrane targeting, Golgi localization, and neurite transport of neuromodulin.
神经调节蛋白（GAP - 43）是一种神经特异性钙调蛋白结合蛋白，通过一种未知机制经快速轴突运输靶向至神经元生长锥。该蛋白通过半胱氨酸3和半胱氨酸4的棕榈酰化作用与膜相关联。本研究的目的是检测神经调节蛋白以及在该蛋白膜靶向结构域中经修饰的神经调节蛋白突变体在神经元和非神经元细胞中的细胞内定位。发现神经调节蛋白的N端棕榈酰化结构域足以实现膜和高尔基体靶向以及神经突运输。由神经调节蛋白的N端20个氨基酸和β - 半乳糖苷酶组成的融合蛋白在神经突末端积累，表明该序列足以靶向生长锥膜。神经调节蛋白棕榈酰化结构域中的突变消除了其酰化作用和膜结合，减少了其在高尔基体中的定位。阻止神经调节蛋白 - β - 半乳糖苷酶融合蛋白在高尔基体中积累的突变也干扰了融合蛋白的神经突运输。这些数据证明了神经调节蛋白的膜靶向、高尔基体定位和神经突运输之间的相关性。
