As one of four filament types, microtubules are a core component of the cytoskeleton and are essential for cell function. Yet how microtubules are nucleated from their building blocks, the αβ-tubulin heterodimer, has remained a fundamental open question since the discovery of tubulin 50 years ago. Recent structural studies have shed light on how γ-tubulin and the γ-tubulin complex proteins (GCPs) GCP2 to GCP6 form the γ-tubulin ring complex (γ-TuRC). In parallel, functional and single-molecule studies have informed on how the γ-TuRC nucleates microtubules in real time, how this process is regulated in the cell and how it compares to other modes of nucleation. Another recent surprise has been the identification of a second essential nucleation factor, which turns out to be the well-characterized microtubule polymerase XMAP215 (also known as CKAP5, a homolog of chTOG, Stu2 and Alp14). This discovery helps to explain why the observed nucleation activity of the γ-TuRC in vitro is relatively low. Taken together, research in recent years has afforded important insight into how microtubules are made in the cell and provides a basis for an exciting era in the cytoskeleton field.

中文翻译：

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分子洞察 γ-TuRC 如何制造微管。

作为四种细丝类型之一，微管是细胞骨架的核心组成部分，对细胞功能至关重要。然而，自 50 年前发现微管蛋白以来，微管是如何从其构建单元 αβ-微管蛋白异二聚体中成核的，这一直是一个基本的悬而未决的问题。最近的结构研究揭示了 γ-微管蛋白和 γ-微管蛋白复合物 (GCP) GCP2 至 GCP6 如何形成 γ-微管蛋白环复合物 (γ-TuRC)。与此同时，功能和单分子研究已经告知了 γ-TuRC 如何实时使微管成核，这一过程如何在细胞中受到调节，以及它与其他成核模式的比较。最近的另一个惊喜是第二个重要的成核因子的鉴定，结果证明它是充分表征的微管聚合酶 XMAP215（也称为 CKAP5，chTOG、Stu2 和 Alp14 的同源物）。这一发现有助于解释为什么观察到的 γ-TuRC 在体外的成核活性相对较低。总之，近年来的研究为细胞中微管的形成方式提供了重要的见解，并为细胞骨架领域的激动人心的时代奠定了基础。