Dibasic amino acid residues at the carboxy-terminal end of kinase homology domain participate in the plasma membrane localization and function of phosphatidylinositol 5-kinase γ
Dibasic amino acid residues at the carboxy-terminal end of kinase homology domain participate in the plasma membrane localization and function of phosphatidylinositol 5-kinase γ
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DOI：
10.1016/j.bbrc.2004.04.187
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发表时间：
2004-06-25
影响因子：
3.1
通讯作者：
Kitamoto, K
中科院分区：
文献类型：
--
作者：
Arioka, M;Nakashima, S;Kitamoto, K
I型磷脂酰肌醇4-磷酸(PI(4)P)5-激酶(PIP5Ks)催化磷脂酰肌醇4，5-二磷酸(PI(4，5)P-2)的合成，磷脂酰肌醇(PI(4，5)P-2)是一种重要的脂质分子，参与肌动蛋白细胞骨架和膜运输的调节。该蛋白定位于质膜，其活性已被证明受小GTP酶、ARF和/或磷脂酸的调节。对PIP5KGamma与EGFP融合的氨基或羧基末端序列的缺失分析表明，PIP5K家族中380个氨基酸高度保守的中心同源结构域(KHD)的存在是PIP5KGamma质膜定位的必要条件和充分条件。特别是，位于KHD羧基末端的二碱基Arg-Lys序列对于PIP5KGamma的质膜靶向是至关重要的，因为这个二碱基序列的缺失或电荷反转突变导致了蛋白质在细胞质中的错误定位。错位突变株也不能补充PIP5K功能缺陷的酿酒酵母mss 4-1突变株对温度敏感的生长。KHD C-末端二碱基序的存在在哺乳动物和无脊椎动物PIP5K家族成员中都是保守的，但在不针对质膜的II型PIPK中不存在，这表明保守的二碱基序为PIP5K的正确定位和细胞功能提供了必要的机制。(C)2004 Elsevier Inc.保留所有权利。
Type I phosphatidylinositol 4-phosphate (PI(4)P) 5-kinases (PIP5Ks) catalyze the synthesis of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P-2), an essential lipid molecule involved in various cellular processes such as regulation of actin cytoskeleton and membrane traffic. The protein localizes to the plasma membrane where its activity has been shown to be regulated by small GTPase ARFs and/or phosphatidic acid. Deletion analysis of amino- or carboxy-terminal sequences of PIP5Kgamma fused with EGFP demonstrated that the presence of central kinase homology domain (KHD), a 380 amino acid-long region highly conserved among PIP5K family, was necessary and sufficient for the plasma membrane localization of PIP5Kgamma. Particularly, the dibasic Arg-Lys sequence located at the carboxy-terininal end of KHD was shown to be crucial for the plasma membrane targeting of PIP5Kgamma, since the deletion or charge-reversal mutation of this dibasic sequence resulted in the mislocalization of the protein to the cytoplasm. Mislocalized mutants also failed to complement the temperature-sensitive growth of Saccharomyces cerevisiae mss4-1 mutant defective in PIP5K function. The presence of dibasic residues at the C-terminal end of KHD was conserved among mammalian as well as invertebrate PIP5K family members, but not in the type II PIPKs that are not targeted to the plasma membrane, suggesting that the conserved dibasic motif provides a mechanism essential for the proper localization and cellular function of PIP5Ks. (C) 2004 Elsevier Inc. All rights reserved.