D'Souza Kenneth, Epand Richard M
Department of Biochemistry and Biomedical Sciences, McMaster University , Hamilton, Ontario L8S 4K1, Canada.
Biochemistry. 2015 Feb 10;54(5):1151-3. doi: 10.1021/bi5015634. Epub 2015 Jan 30.
Phosphatidylinositol (PI) and its phosphorylated forms are required for many critical cellular processes. PI is highly enriched at its sn-1 and sn-2 positions, the major species being 1-stearoyl-2-arachidonoyl PI (18:0/20:4 PI). This enrichment is achieved in part through enzymatic acyl chain specificity in PI synthesis. Here we characterize the acyl chain specificity of phosphatidylinositol synthase (PIS), which is involved in the terminal step of PI synthesis. Unlike several other enzymes involved in PI synthesis, PIS appears to exhibit no acyl chain specificity toward its substrates. Thus, enrichment of newly formed PI occurs prior to the terminal synthesis step.
磷脂酰肌醇（PI）及其磷酸化形式参与许多关键的细胞过程。PI在其sn-1和sn-2位高度富集，主要种类为1-硬脂酰-2-花生四烯酰PI（18:0/20:4 PI）。这种富集部分是通过PI合成中酶的酰基链特异性实现的。在这里，我们描述了参与PI合成终末步骤的磷脂酰肌醇合酶（PIS）的酰基链特异性。与其他几种参与PI合成的酶不同，PIS似乎对其底物没有酰基链特异性。因此，新形成的PI的富集发生在终末合成步骤之前。
