Cytokinesis in many eukaryotes is dependent on a contractile actomyosin ring (AMR), composed of F-actin, myosin II, and other actin and myosin II regulators. Through fluorescence recovery after photobleaching experiments, many components of the AMR have been shown to be mobile and to undergo constant exchange with the cytosolic pools. However, how the mobility of its components changes at distinct stages of mitosis and cytokinesis has not been addressed. Here, we describe the mobility of eight Schizosaccharomyces pombe AMR proteins at different stages of mitosis and cytokinesis using an approach we have developed. We identified 3 classes of proteins, which showed 1) high (Ain1, Myo2, Myo51), 2) low (Rng2, Mid1, Myp2, Cdc12), and 3) cell cycle dependent (Cdc15) mobile fractions. We observed that the F-BAR protein Cdc15 undergoes a 20∼30% reduction in its mobile fraction after spindle breakdown and initiation of AMR contraction. Moreover, our data indicate that this change in Cdc15 mobility is dependent on the SIN-signalling pathway. Our work offers a novel strategy to estimate cell cycle-dependent mobile protein fractions in cellular structures and provides a valuable dataset, that is of interest to researchers working on cytokinesis.

许多真核生物中的细胞分裂依赖于收缩性肌动球蛋白环 (AMR)，该环由 F-肌动蛋白、肌球蛋白 II 以及其他肌动蛋白和肌球蛋白 II 调节因子组成。通过光漂白实验后的荧光恢复，AMR 的许多成分已被证明是可移动的，并与胞质池进行不断的交换。然而，其成分的流动性在有丝分裂和胞质分裂的不同阶段如何变化尚未得到解决。在这里，我们使用我们开发的方法描述了八种粟酒裂殖酵母AMR 蛋白在有丝分裂和胞质分裂不同阶段的流动性。我们鉴定了 3 类蛋白质，显示 1) 高（Ain1、Myo2、Myo51）、2）低（Rng2、Mid1、Myp2、Cdc12）和 3）细胞周期依赖性 (Cdc15) 移动分数。我们观察到，在纺锤体断裂和 AMR 收缩开始后，F-BAR 蛋白 Cdc15 的移动分数减少了 20∼30%。此外，我们的数据表明 Cdc15 迁移率的这种变化取决于 SIN 信号通路。我们的工作提供了一种新的策略来估计细胞结构中细胞周期依赖性移动蛋白部分，并提供了有价值的数据集，这对于从事胞质分裂的研究人员来说是感兴趣的。