Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA.
Department of Chemistry and Biochemistry, California Polytechnic State University SLO, San Luis Obispo, CA, USA.
J Cell Biol. 2023 Dec 4;222(12). doi: 10.1083/jcb.202306036. Epub 2023 Oct 6.
Understanding how numerous actin-binding proteins (ABPs) work in concert to control the assembly, organization, and turnover of the actin cytoskeleton requires quantitative information about the levels of each component. Here, we measured the cellular concentrations of actin and the majority of the conserved ABPs in Saccharomyces cerevisiae, as well as the free (cytosolic) fractions of each ABP. The cellular concentration of actin is estimated to be 13.2 µM, with approximately two-thirds in the F-actin form and one-third in the G-actin form. Cellular concentrations of ABPs range from 12.4 to 0.85 µM (Tpm1> Pfy1> Cof1> Abp1> Srv2> Abp140> Tpm2> Aip1> Cap1/2> Crn1> Sac6> Twf1> Arp2/3> Scp1). The cytosolic fractions of all ABPs are unexpectedly high (0.6-0.9) and remain so throughout the cell cycle. Based on these numbers, we speculate that F-actin binding sites are limited in vivo, which leads to high cytosolic levels of ABPs, and in turn helps drive the rapid assembly and turnover of cellular F-actin structures.
了解众多肌动蛋白结合蛋白 (ABP) 如何协同作用来控制肌动蛋白细胞骨架的组装、组织和周转，需要有关每种成分水平的定量信息。在这里，我们测量了酿酒酵母中的肌动蛋白和大多数保守 ABP 的细胞浓度，以及每种 ABP 的游离（胞质）部分。肌动蛋白的细胞浓度估计为 13.2 µM，其中约三分之二处于 F-肌动蛋白形式，三分之一处于 G-肌动蛋白形式。ABP 的细胞浓度范围从 12.4 到 0.85 µM（Tpm1> Pfy1> Cof1> Abp1> Srv2> Abp140> Tpm2> Aip1> Cap1/2> Crn1> Sac6> Twf1> Arp2/3> Scp1）。所有 ABP 的胞质部分都出人意料地高（0.6-0.9），并且在整个细胞周期中保持不变。根据这些数字，我们推测 F-肌动蛋白结合位点在体内是有限的，这导致 ABP 的胞质水平升高，进而有助于驱动细胞 F-肌动蛋白结构的快速组装和周转。
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