Xenopus actin-interacting protein 1 (XAip1) enhances cofilin fragmentation of filaments by capping filament ends
Xenopus actin-interacting protein 1 (XAip1) enhances cofilin fragmentation of filaments by capping filament ends
复制标题
DOI：
10.1074/jbc.m203111200
复制
发表时间：
2002-11-08
影响因子：
4.8
通讯作者：
Bamburg, JR
中科院分区：
文献类型：
--
作者：
Okada, K;Blanchoin, L;Bamburg, JR
非洲爪蟾肌动蛋白相互作用蛋白1（XAip 1）被认为是促进肌动蛋白丝被cofilin断裂。为了研究XAip 1的机制，我们通过荧光显微镜测量了聚合物长度，并通过伸长率测定测量了细丝末端的浓度。Cofilin通过切断肌动蛋白丝产生末端。XAip 1单独不切断肌动蛋白丝或防止机械切断的丝的退火/重新分布，并且对可用于亚基添加的末端的浓度没有影响。在XAip 1的存在下，cofilin的明显的丝断裂增强，但XAip 1减少而不是增加能够添加亚基的末端的浓度。电子显微镜与金标记的抗体显示，低浓度的XAip 1绑定优先的细丝的一端。高浓度的XAip 1沿着丝的长度沿着结合。在凝溶胶-肌动蛋白的存在下，以帽丝倒刺结束，XAip 1不增强cofilin活性。我们的结论是，XAip 1帽的倒刺端切断丝切。这种加帽阻断了退火和解聚，并允许被cofilin更广泛地切断。
Xenopus actin-interacting protein 1 (XAip1) is thought to promote fragmentation of actin filaments by cofilin. To examine the mechanism of XAip1, we measured polymer lengths by fluorescence microscopy and the concentration of filament ends with an elongation assay. Cofilin creates ends by severing actin filaments. XAip1 alone does not sever actin filaments or prevent annealing/ redistribution of mechanically severed filaments and has no effect on the concentration of ends available for subunit addition. In the presence of XAip1, the apparent filament fragmentation by cofilin is enhanced, but XAip1 reduces rather than increases the concentration of ends capable of adding subunits. Electron microscopy with gold-labeled antibodies showed that a low concentration of XAip1 bound preferentially to one end of the filament. A high concentration of XAip1 bound along the length of the filament. In the presence of gelsolin-actin to cap filament barbed ends, XAip1 does not enhance cofilin activity. We conclude that XAip1 caps the barbed end of filaments severed by cofilin. This capping blocks annealing and depolymerization and allows more extensive severing by cofilin.