Intrinsic signals in the unique domain target p56(lck) to the plasma membrane independently of CD4
Intrinsic signals in the unique domain target p56(lck) to the plasma membrane independently of CD4
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DOI：
10.1083/jcb.137.5.1029
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发表时间：
1997-06-02
影响因子：
7.8
通讯作者：
Marsh, M
中科院分区：
文献类型：
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作者：
Bijlmakers, MJJE;IsobeNakamura, M;Marsh, M
在T淋巴细胞中，Src家族蛋白酪氨酸激酶p56（lck）（Lck）主要与质膜的细胞质面相关。为了确定这种分布是如何实现的，我们通过免疫荧光分析了Lck在淋巴细胞和转染的非淋巴细胞中的位置。我们发现，在T细胞中，Lck被正确地靶向，独立于与其相互作用的细胞表面蛋白CD 4和CD 8。类似地，在转染的NIH-3 T3成纤维细胞中，Lck定位于质膜，表明靶向不需要T细胞特异性蛋白。当Lck在HeLa和MDCK细胞中表达时，观察到亚细胞分布的一些变化。在这些细胞中，Lck与质膜和高尔基体，而随后的表达CD 4导致高尔基体相关染色的损失。总之，这些数据表明Lck含有靶向质膜的内在信号。此外，递送至该位点可通过与胞外转运囊泡的结合来实现。在NIH-3 T3细胞中，半胱氨酸5处的棕榈酰化位点改变为赖氨酸（LC 2）的突变体Lck分子定位于质膜和高尔基体区域。然而，在半胱氨酸3的棕榈酰化位点被改变为丝氨酸（LC 1）的突变体的本地化是从野生型LCK无法区分。嵌合体仅由连接到c-Src或绿色荧光蛋白的Lck的独特结构域组成，类似地定位于NIH-3 T3细胞的质膜。因此，Lck的靶向作用似乎主要由其独特的结构域决定，并可能受到不同棕榈酰化位点的影响。
In T lymphocytes, the Src-family protein tyrosine kinase p56(lck) (Lck) is mostly associated with the cytoplasmic face of the plasma membrane. To determine how this distribution is achieved, we analyzed the location of Lck in lymphoid and in transfected nonlymphoid cells by immunofluorescence. We found that in T cells Lck was targeted correctly, independently of the cell surface proteins CD4 and CD8 with which it interacts. Similarly, in transfected NIH-3T3 fibroblasts, Lck was localized at the plasma membrane, indicating that T cell-specific proteins are not required for targeting. Some variation in subcellular distribution was observed when Lck was expressed in HeLa and MDCK cells. In these cells, Lck associated with both the plasma membrane and the Golgi apparatus, while subsequent expression of CD4 resulted in the loss of Golgi-associated staining. Together, these data indicate that Lck contains intrinsic signals for targeting to the plasma membrane. Furthermore, delivery to this site may be achieved via association with exocytic transport vesicles.A mutant Lck molecule in which the palmitoylation site at cysteine 5 was changed to lysine (LC2) localized to the plasma membrane and the Golgi region in NIH-3T3 cells. However, the localization of a mutant in which the palmitoylation site at cysteine 3 was changed to serine (LC1) was indistinguishable from wild-type Lck. Chimeras composed of only the unique domain of Lck linked to either c-Src or the green fluorescent protein similarly localized to the plasma membrane of NIH-3T3 cells. Thus, the targeting of Lck appears to be determined primarily by its unique domain and may be influenced by the use of different palmitoylation sites.