Sun1 forms immobile macromolecular assemblies at the nuclear envelope
Sun1 forms immobile macromolecular assemblies at the nuclear envelope
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DOI：
10.1016/j.bbamcr.2008.09.001
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发表时间：
2008-12-01
影响因子：
5.1
通讯作者：
Karakesisoglou, Iakowos
中科院分区：
文献类型：
--
作者：
Lu, Wenshu;Gotzmann, Josef;Karakesisoglou, Iakowos
太阳域蛋白形成了一个新的保守的内核膜蛋白家族，它建立了核质和细胞骨架之间的物理连接。在目前的研究中，我们提供了证据，证明在核膜(NE)内，STINT蛋白在间期细胞中形成高度固定的寡聚复合体。通过在光漂白分析后进行反向荧光恢复，我们在体内证明了核周和核质Sun I片段对于维持NE处Sun I的不动是必不可少的。我们的数据特别强调了C末端螺旋线圈Sun I片段的自缔合性质，证明了它形成二聚体和四聚体的能力。此外，SUN1的三级结构涉及链间二硫键，这可能有助于形成更高的同质低聚物，尽管当所涉及的半胱氨酸发生突变时，SUN1 C末端的整体动力学仍然不受影响。虽然一个主要的SUN1池与核孔复合体蛋白共定位，但很大一部分SUN1蛋白组合与SUN2的免疫反应中心共同定位，SUN2是NE的另一个太阳域平行结构。我们证明了SUN1的卷曲线圈结构域允许这些与SUN2的异嗜性关联。因此，SUN1为在INM形成不同的大分子组装提供了一个非动态的平台。我们的数据支持这样一个模型，即含有太阳蛋白的多元复合体可能为细胞骨架细丝提供多样的外核膜附着位置。皇冠版权所有(C)2008由爱思唯尔出版。保留所有权利。
SUN-domain proteins form a novel and conserved family of inner nuclear membrane (INM) proteins, which establish physical connections between the nucleoplasm and the cytoskeleton. In the current study, we provide evidence that within the nuclear envelope (NE) Stint proteins form highly immobile oligomeric complexes in interphase cells. By performing inverse fluorescence recovery after photobleaching analysis, we demonstrate in vivo that both perinuclear and nucleoplasmic Sun I segments are essential for maintenance of Sun I immobility at the NE. Our data in Particular underline the self-association properties of the C-terminal coiled-coil Sun I segment, the ability of which to form dimers and tetramers is demonstrated. Furthermore, the Sun1 tertiary Structure involves interchain disulfide bonds that might contribute to higher homo-oligomer formation, although the overall dynamics of the Sun1 C-terminus remains unaffected when the cysteins involved are mutated. While a major Sun1 pool colocalizes with nuclear pore complex proteins, a large fraction of the Sun1 protein assemblies colocalize with immunoreactive foci of Sun2, another SUN-domain paralogue at the NE. We demonstrate that the Sun1 coiled-coil domain permits these heterophilic associations with Sun2. Sun1 therefore provides a non-dynamic platform for the formation of different macromolecular assemblies at the INM Our data support a model in which SUN-protein-containing multivariate complexes may provide versatile outer nuclear membrane attachment sites for cytoskeletal filaments. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.