The central transport channel (CTC) of nuclear pore complexes (NPCs) is made up of three nucleoporins Nup62, Nup58 and Nup54. In which manner and capacity, these nucleoporins form the CTC, is not yet clear. We explored the CTC Nups from various species and observed that distinct biochemical characteristics of CTC Nups are evolutionarily conserved. Moreover, comparative biochemical analysis of CTC complexes showed various stoichiometric combinations of Nup62, Nup54 and Nup58 coexisting together. We observed the conserved amino‐terminal domain of mammalian Nup93 is crucial for the anchorage of CTC and its localization to NPCs. We could reconstitute and purify mammalian CTC·Nup93 quaternary complex by co‐expressing full length or N‐terminal domain of Nup93 along with CTC complex. Further, we characterized CTC·Nup93 complex using small angle X‐ray scattering and electron microscopy that revealed a “V” shape of CTC·Nup93 complex. Overall, this study demonstrated for the first time evolutionarily conserved plasticity and stoichiometric diversity in CTC Nups.

中文翻译：

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核孔复合体Nup93复合体中心转运通道的分子结构分析

核孔复合物 (NPC) 的中央运输通道 (CTC) 由三个核孔蛋白 Nup62、Nup58 和 Nup54 组成。这些核孔蛋白以何种方式和能力形成 CTC，尚不清楚。我们探索了来自不同物种的 CTC Nup，并观察到 ​​CTC Nup 的不同生化特征在进化上是保守的。此外，CTC 复合物的比较生化分析显示 Nup62、Nup54 和 Nup58 的各种化学计量组合共存。我们观察到哺乳动物 Nup93 的保守氨基末端结构域对于 CTC 的锚定及其在 NPC 的定位至关重要。我们可以通过将 Nup93 的全长或 N 端结构域与 CTC 复合物共表达来重构和纯化哺乳动物 CTC·Nup93 四元复合物。更远，我们使用小角度 X 射线散射和电子显微镜表征 CTC·Nup93 复合物，显示 CTC·Nup93 复合物呈“V”形。总体而言，这项研究首次证明了 CTC Nups 在进化上保守的可塑性和化学计量多样性。