Nielsen Erik
Deparment of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
Biochem J. 2008 Jul 1;413(1):e5-6. doi: 10.1042/BJ20080953.
Phosphoinositides are well-known components of cellular signal transduction pathways and, more recently, have been shown to play important roles in organelle identity and targeting determinants for various cytosolic proteins. Conversion of PtdIns into its various phosphorylated derivatives, such as PtdIns4P and PtdIns(4,5)P(2), is accomplished by a series of distinct lipid kinase and lipid phosphatase activities that are localized to specific subcellular membranes. As a result, production of distinct PtdIns forms is thought to be largely dependent on the access of these enzymes to their PtdIns or PtdInsP substrates. Interestingly, an investigation of two different PIS (PtdIns synthase) isoforms by Lofke et al. in this issue of the Biochemical Journal now indicates that the ability of PtdIns to be converted into downstream PtdInsPs may depend upon the PIS isoform from which it was synthesized.
磷酸肌醇是细胞信号转导途径中众所周知的组成部分，最近研究表明，它们在细胞器识别以及各种胞质蛋白的靶向决定因素中发挥重要作用。磷脂酰肌醇（PtdIns）转化为其各种磷酸化衍生物，如磷脂酰肌醇-4-磷酸（PtdIns4P）和磷脂酰肌醇-4,5-二磷酸（PtdIns(4,5)P(2)），是通过一系列定位于特定亚细胞膜的独特脂质激酶和脂质磷酸酶活性来完成的。因此，不同形式的PtdIns的产生在很大程度上被认为取决于这些酶接近其PtdIns或PtdInsP底物的能力。有趣的是，Lofke等人在本期《生物化学杂志》中对两种不同的磷脂酰肌醇合成酶（PIS）同工型进行的一项研究现在表明，PtdIns转化为下游PtdInsP的能力可能取决于合成它的PIS同工型。
