Myristoylation cannot functionally replace the isoprenylation of Rab5.
Myristoylation cannot functionally replace the isoprenylation of Rab5.
复制标题
肉豆蔻酰化不能在功能上取代 Rab5 的异戊二烯化。
DOI：
10.1006/abbi.1995.1070
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发表时间：
1995
影响因子：
3.9
通讯作者：
Stahl,PD
中科院分区：
文献类型：
--
作者：
Li,G;Barbieri,MA;Stahl,PD
C-末端异戊二烯化是小GTTRab 5与早期内体结合并在胞吞作用中发挥其调节功能所必需的。在这项研究中，我们测试了如果异戊二烯化被另一种类型的脂质修饰（肉豆蔻酰化）取代，Rab 5是否可以保留其膜结合和生物学功能。分别构建了含有异戊二烯化和豆蔻酰化（Gag-Rab 5）、仅豆蔻酰化（Gag-Rab 5 ΔC4）和不含这两种修饰（Rab 5 ΔC4）的Rab 5突变体。这些突变体和野生型Rab 5通过辛德毕斯病毒载体在培养的BHK-21细胞中表达，并检查它们的膜结合和生物活性（内吞作用的刺激）。野生型Rab 5是异戊二烯化的，膜相关的，并且具有生物活性。随着额外的豆蔻酰化，Gag-Rab 5表现出对膜的亲和力增加，但生物活性降低。Rab 5 ΔC4不含脂质修饰，不能与膜结合，也没有生物活性。在豆蔻酰化（Gag-Rab 5 ΔC4）的情况下，膜结合显著增加（约30%）。然而，这种增加的膜结合没有导致Rab 5活性的任何恢复。根据这些数据，我们得出结论，N-末端豆蔻酰化不能在功能上取代Rab 5的C-末端异戊二烯化。此外，Rab 5的豆蔻酰化（Gag-Rab 5）干扰其正常功能。
C-terminal isoprenylation is necessary for the small GTPase Rab5 to associate with early endosomes and to exert its regulatory function in endocytosis. In this study, we tested whether Rab5 could retain its membrane association and biological function if the isoprenylation were replaced by another type of lipid modification (myristoylation). Rab5 mutants were constructed that contained both isoprenylation and myristoylation (Gag-Rab5), myristoylation only (Gag-Rab5ΔC4), and neither of the modifications (Rab5ΔC4), respectively. These mutants and wild-type Rab5 were expressed, via a Sindbis virus vector, in cultured BHK-21 cells and their membrane association and biological activity (stimulation of endocytosis) were examined. Wild-type Rab5 was isoprenylated, membrane associated, and biologically active. With additional myristoylation, Gag-Rab5 showed increased affinity for membranes but decreased biological activity. Rab5ΔC4 contained no lipid modifications, failed to associate with membranes, and had no biological activity. With myristoylation (Gag-Rab5ΔC4), there was a significant increase in membrane association (∼30%). However, this increased membrane association did not result in any recovery of Rab5 activity. In light of these data, we conclude that N-terminal myristoylation cannot functionally replace the C-terminal isoprenylation of Rab5. Furthermore, myristoylation of Rab5 (Gag-Rab5) interferes with its normal function.