Fukui Yasuhisa, Wakamatsu Isamu, Tachikawa Hiroyuki, Okamura Yoshihiko, Tanaka Takayuki, Ihara Sayoko
Division of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan.
IUBMB Life. 2007 Feb;59(2):99-103. doi: 10.1080/15216540701222880.
SWAP-70 translocates to the plasma membrane in a phosphoinositide 3-kinase (PI 3-kinase)-dependent manner and contributes to membrane ruffling. It binds to phosphatidylinositol trisphosphate (PtdIns(3,4,5)P(3)) through its PH domain, which is essential for the membrane translocation after EGF stimulation. We examined the behavior of the SWAP-70s which have mutations in the beta3/beta4 loop of the PH domain. The two mutants fused to green fluorescent protein (GFP) carrying the mutations failed to translocate to the plasma membrane. The sole PH domains carrying the same mutations behaved similarly. The PtdIns(3,4,5)P(3) binding activity of two mutants was comparable to that of the wild-type protein. These results suggest that translocation of SWAP-70 largely depends on the activity of the PH domain, and that not only PtdIns(3,4,5)P(3) binding activity, but also some additional activity of the PH domain is required for the translocation.
SWAP-70以磷酸肌醇3激酶（PI 3激酶）依赖的方式转位至质膜，并促进膜 ruffling。它通过其PH结构域与磷脂酰肌醇三磷酸（PtdIns(3,4,5)P(3)）结合，这对于表皮生长因子（EGF）刺激后的膜转位至关重要。我们研究了在PH结构域的β3/β4环中具有突变的SWAP-70的行为。携带这些突变的与绿色荧光蛋白（GFP）融合的两个突变体未能转位至质膜。携带相同突变的单独PH结构域表现类似。两个突变体的PtdIns(3,4,5)P(3)结合活性与野生型蛋白相当。这些结果表明，SWAP-70的转位很大程度上取决于PH结构域的活性，并且转位不仅需要PtdIns(3,4,5)P(3)结合活性，还需要PH结构域的一些额外活性。
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