Field C M, al-Awar O, Rosenblatt J, Wong M L, Alberts B, Mitchison T J
Department of Biochemistry and Biophysics, University of California at San Francisco 94143-0448, USA.
J Cell Biol. 1996 May;133(3):605-16. doi: 10.1083/jcb.133.3.605.
Septin proteins are necessary for cytokinesis in budding yeast and Drosophila and are thought to be the subunits of the yeast neck filaments. To test whether septins actually form filaments, an immunoaffinity approach was used to isolate a septin complex from Drosophila embryos. The purified complex is comprised of the three previously identified septin polypeptides Pnut, Sep2, and Sep1. Hydrodynamic and sequence data suggest that the complex is composed of a heterotrimer of homodimers. The complex copurifies with one molecule of bound guanine nucleotide per septin polypeptide. It binds and hydrolyzes exogenously added GTP. These observations together with conserved sequence motifs identify the septins as members of the GTPase superfamily. We discuss a model of filament structure and speculate as to how the filaments are organized within cells.
Septin蛋白对于芽殖酵母和果蝇的胞质分裂是必需的，并且被认为是酵母颈部细丝的亚基。为了测试septin是否真的形成细丝，采用免疫亲和方法从果蝇胚胎中分离出一个septin复合体。纯化的复合体由三种先前鉴定出的septin多肽Pnut、Sep2和Sep1组成。流体动力学和序列数据表明该复合体由同型二聚体的异源三聚体组成。该复合体每一个septin多肽与一分子结合的鸟嘌呤核苷酸共纯化。它结合并水解外源添加的GTP。这些观察结果以及保守的序列基序将septin鉴定为GTPase超家族的成员。我们讨论了细丝结构模型，并推测细丝在细胞内是如何组织的。
