Hoepfner Dominic, Schildknegt Danny, Braakman Ineke, Philippsen Peter, Tabak Henk F
Department of Cellular Protein Chemistry, University of Utrecht, Padualaan 8, NL-3548 CH Utrecht, The Netherlands.
Cell. 2005 Jul 15;122(1):85-95. doi: 10.1016/j.cell.2005.04.025.
How peroxisomes are formed in eukaryotic cells is unknown but important for insight into a variety of diseases. Both human and yeast cells lacking peroxisomes due to mutations in PEX3 or PEX19 genes regenerate the organelles upon reintroduction of the corresponding wild-type version. To evaluate how and from where new peroxisomes are formed, we followed the trafficking route of newly made YFP-tagged Pex3 and Pex19 proteins by real-time fluorescence microscopy in Saccharomyces cerevisiae. Remarkably, Pex3 (an integral membrane protein) could first be observed in the endoplasmic reticulum (ER), where it concentrates in foci that then bud off in a Pex19-dependent manner and mature into fully functional peroxisomes. Pex19 (a farnesylated, mostly cytosolic protein) enriches first at the Pex3 foci on the ER and then on the maturing peroxisomes. This trafficking route of Pex3-YFP is the same in wild-type cells. These results demonstrate that peroxisomes are generated from domains in the ER.
过氧化物酶体在真核细胞中如何形成尚不清楚，但对于深入了解多种疾病至关重要。由于PEX3或PEX19基因突变而缺乏过氧化物酶体的人类和酵母细胞，在重新引入相应的野生型版本后会再生这些细胞器。为了评估新的过氧化物酶体如何形成以及从何处形成，我们通过实时荧光显微镜在酿酒酵母中追踪了新合成的带有黄色荧光蛋白（YFP）标签的Pex3和Pex19蛋白的运输途径。值得注意的是，Pex3（一种整合膜蛋白）首先可以在内质网（ER）中观察到，它在内质网中聚集形成焦点，然后以依赖于Pex19的方式出芽，并成熟为功能完全正常的过氧化物酶体。Pex19（一种法尼基化的、主要位于胞质溶胶中的蛋白）首先在ER上的Pex3焦点处富集，然后在成熟的过氧化物酶体上富集。Pex3-YFP的这种运输途径在野生型细胞中是相同的。这些结果表明，过氧化物酶体是由内质网中的区域产生的。
