Raychaudhuri Sumana, Prinz William A
Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Proc Natl Acad Sci U S A. 2008 Oct 14;105(41):15785-90. doi: 10.1073/pnas.0808321105. Epub 2008 Oct 3.
The endoplasmic reticulum (ER) plays an important role in peroxisome biogenesis; some peroxisomal membrane proteins are inserted into the ER and trafficked to peroxisomes in vesicles. These vesicles could also provide the phospholipids required for the growth of peroxisomal membranes, because peroxisomes lack phospholipid biosynthesis enzymes. To test this, we established a novel assay to monitor phospholipid transfer between the ER and peroxisomes and found that phospholipids are rapidly trafficked between these compartments. This transport is not blocked in mutants with conditional defects in Sec proteins required for vesicular trafficking from the ER or in Pex3p, a protein required for peroxisome membrane biogenesis. ER to peroxisome lipid transport was reconstituted in vitro and does not require cytosolic factors or ATP. Our findings indicate that lipids are directly transferred from the ER to peroxisomes by a nonvesicular pathway and suggest that ER to peroxisome vesicular transport is not required to provide lipids for peroxisomal growth.
内质网（ER）在过氧化物酶体生物发生中起重要作用；一些过氧化物酶体膜蛋白插入内质网，并通过囊泡运输到过氧化物酶体。这些囊泡还可以提供过氧化物酶体膜生长所需的磷脂，因为过氧化物酶体缺乏磷脂生物合成酶。为了验证这一点，我们建立了一种新的检测方法来监测内质网和过氧化物酶体之间的磷脂转移，发现磷脂在这些区室之间快速运输。这种运输在从内质网进行囊泡运输所需的Sec蛋白有条件缺陷的突变体中或在过氧化物酶体膜生物发生所需的Pex3p蛋白中均未被阻断。内质网到过氧化物酶体的脂质运输在体外被重建，并且不需要胞质因子或ATP。我们的研究结果表明，脂质通过非囊泡途径直接从内质网转移到过氧化物酶体，并表明内质网到过氧化物酶体的囊泡运输不是过氧化物酶体生长所需脂质的来源。
