内质网对包括膜的生物发生、囊泡运输和蛋白分泌在内的很多细胞功能都很关键，它是一个由管状结构构成的互联的网络，遍及真核细胞。这一特定结构的维持机制尚不清楚，尽管依赖于GTP水解的同型膜融合已知是内质网的生物发生和维持所必需的。
现在，用果蝇所进行的一项研究表明，被称为Atlastin的一种GTP酶（在遗传性痉挛性截瘫中发生突变的人类Atlastin 1的一个同源分子）是同型膜融合所必需的，因而也是内质网形成所必需的。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 460, 978-983 (20 August 2009) | doi:10.1038/nature08280
Homotypic fusion of ER membranes requires the dynamin-like GTPase Atlastin
Genny Orso1,8, Diana Pendin1,8, Song Liu2,8, Jessica Tosetto1,3, Tyler J. Moss2, Joseph E. Faust2, Massimo Micaroni4, Anastasia Egorova5, Andrea Martinuzzi1, James A. McNew2 & Andrea Daga1,6,7
1 Eugenio Medea Scientific Institute, Conegliano 31015, Italy
2 Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA
3 Department of Pharmacology, University of Padova, Padova 35131, Italy
4 University of Queensland, Institute for Molecular Bioscience, St Lucia, Brisbane, Queensland 4072, Australia
5 Department of Cell Biology and Oncology, Consorzio "Mario Negri Sud", Santa Maria Imbaro 66030, Italy
6 Dulbecco Telethon Institute, Eugenio Medea Scientific Institute, Padova 35131, Italy
7 Department of Neurology, The David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
8 These authors contributed equally to this work.
Establishment and maintenance of proper architecture is essential for endoplasmic reticulum (ER) function. Homotypic membrane fusion is required for ER biogenesis and maintenance, and has been shown to depend on GTP hydrolysis. Here we demonstrate that Drosophila Atlastin—the fly homologue of the mammalian GTPase atlastin 1 involved in hereditary spastic paraplegia—localizes on ER membranes and that its loss causes ER fragmentation. Drosophila Atlastin embedded in distinct membranes has the ability to form trans-oligomeric complexes and its overexpression induces enlargement of ER profiles, consistent with excessive fusion of ER membranes. In vitro experiments confirm that Atlastin autonomously drives membrane fusion in a GTP-dependent fashion. In contrast, GTPase-deficient Atlastin is inactive, unable to form trans-oligomeric complexes owing to failure to self-associate, and incapable of promoting fusion in vitro. These results demonstrate that Atlastin mediates membrane tethering and fusion and strongly suggest that it is the GTPase activity that is required for ER homotypic fusion.
