Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232.
Mol Biol Cell. 2023 Oct 1;34(11):br17. doi: 10.1091/mbc.E23-06-0233. Epub 2023 Aug 2.
Myosin-1s are monomeric actin-based motors that function at membranes. Myo1 is the single myosin-1 isoform in that works redundantly with Wsp1-Vrp1 to activate the Arp2/3 complex for endocytosis. Here, we identified Ank1 as an uncharacterized cytoplasmic Myo1 binding partner. We found that in cells, Myo1 dramatically redistributed from endocytic patches to decorate the entire plasma membrane and endocytosis was defective. Biochemical analysis and structural predictions suggested that the Ank1 ankyrin repeats bind the Myo1 lever arm and the Ank1 acidic tail binds the Myo1 TH1 domain to prevent TH1-dependent Myo1 membrane binding. Indeed, Ank1 overexpression precluded Myo1 membrane localization and recombinant Ank1 reduced purified Myo1 liposome binding in vitro. Based on biochemical and cell biological analyses, we propose budding yeast Ank1 and human OSTF1 are functional Ank1 orthologs and that cytoplasmic sequestration by small ankyrin repeat proteins is a conserved mechanism regulating myosin-1s in endocytosis.
肌球蛋白-1s 是单体肌动蛋白基马达，在膜上发挥作用。Myo1 是 中唯一的肌球蛋白-1 同工型，与 Wsp1-Vrp1 冗余工作，激活 Arp2/3 复合物进行内吞作用。在这里，我们鉴定出 Ank1 是一种未被描述的细胞质 Myo1 结合伴侣。我们发现，在 细胞中，Myo1 从内吞斑显著重新分布到整个质膜，内吞作用受损。生化分析和结构预测表明，Ank1 的锚蛋白重复序列结合 Myo1 的 lever arm，Ank1 的酸性尾巴结合 Myo1 的 TH1 结构域，以防止 TH1 依赖性 Myo1 膜结合。事实上，Ank1 的过表达阻止了 Myo1 的膜定位，重组 Ank1 减少了体外纯化的 Myo1 脂质体结合。基于生化和细胞生物学分析，我们提出 budding yeast Ank1 和人类 OSTF1 是功能性 Ank1 直系同源物，并且细胞质锚蛋白重复蛋白的隔离是调节内吞作用中肌球蛋白-1s 的保守机制。
