BMSB Graduate Program, University of California, Los Angeles, CA 90095, USA; Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.
Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA.
Curr Biol. 2021 May 24;31(10):R517-R522. doi: 10.1016/j.cub.2021.02.047.
Actin is one of the most abundant proteins in eukaryotes. Discovered in muscle and described as far back as 1887, actin was first purified in 1942. It plays myriad roles in essentially every eukaryotic cell. Actin is central to development, muscle contraction, and cell motility, and it also functions in the nucleus, to name a spectrum of examples. The flexibility of actin function stems from two factors: firstly, it is dynamic, transitioning between monomer and filament, and, secondly, there are hundreds of actin-binding proteins that build and organize specific actin-based structures. Of prime importance are actin nucleators - proteins that stimulate de novo formation of actin filaments. There are three known classes of actin nucleators: the Arp2/3 complex, formins, and tandem WASP homology 2 (WH2) nucleators. Each class nucleates by a distinct mechanism that contributes to the organization of the larger structure being built. Evidence shows that the Arp2/3 complex produces branched actin filaments, remaining bound at the branch point, while formins create linear actin filaments, remaining bound at the growing end. Here, we focus on the formin family of actin nucleators.
肌动蛋白是真核生物中最丰富的蛋白质之一。早在 1887 年就在肌肉中发现并进行了描述，肌动蛋白于 1942 年首次被纯化。它在几乎所有真核细胞中都发挥着多种作用。肌动蛋白是发育、肌肉收缩和细胞运动的核心，它也在核中发挥作用，仅举几个例子。肌动蛋白功能的灵活性源于两个因素：首先，它是动态的，在单体和丝之间转换，其次，有数百种肌动蛋白结合蛋白构建和组织特定的肌动蛋白基结构。至关重要的是肌动蛋白成核因子——能刺激肌动蛋白丝从头形成的蛋白质。有三种已知的肌动蛋白成核因子：Arp2/3 复合物、formin 和串联 WASP 同源结构域 2 (WH2) 成核因子。每一类都通过独特的机制进行成核，有助于构建更大的结构。有证据表明，Arp2/3 复合物产生分支肌动蛋白丝，并在分支点保持结合，而formin 则产生线性肌动蛋白丝，并在生长端保持结合。在这里，我们重点介绍肌动蛋白成核因子的 formin 家族。
