Ena/VASP proteins enhance actin polymerization in the presence of barbed end capping proteins
Ena/VASP proteins enhance actin polymerization in the presence of barbed end capping proteins
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DOI：
10.1074/jbc.m503957200
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发表时间：
2005-08-05
影响因子：
4.8
通讯作者：
Schafer, DA
中科院分区：
文献类型：
--
作者：
Barzik, M;Kotova, TI;Schafer, DA
Ena/VASP蛋白影响迁移细胞的板状伪足和丝状伪足内以及肌动蛋白彗星尾中肌动蛋白丝网络的组织。Ena/ VASP蛋白控制肌动蛋白动力学的分子机制尚不清楚。我们研究了Ena/ VASP蛋白如何调节肌动蛋白聚合在肌动蛋白丝倒刺末端在体外的存在和不存在的倒刺封端蛋白。重组His-标记的VASP增加了肌动蛋白聚合的速率，在存在的倒钩端帽，异二聚体帽蛋白（CP），CapG，和凝溶胶-肌动蛋白复合物。Profilin增强了VASP保护倒刺末端免受CP覆盖的能力，这需要profilin与G-肌动蛋白和VASP的相互作用。VASP EVH 2结构域足以保护倒刺末端不被加帽，并且需要EVH 2内的F-肌动蛋白和G-肌动蛋白结合基序。蛋白激酶A在VASP EVH 2结构域内的磷酸化调节VASP的抗帽和F-肌动蛋白捆绑。我们建议，Ena/ VASP蛋白关联或附近的肌动蛋白丝倒刺末端，促进肌动蛋白组装，并限制访问的倒刺端帽蛋白。
Ena/VASP proteins influence the organization of actin filament networks within lamellipodia and filopodia of migrating cells and in actin comet tails. The molecular mechanisms by which Ena/ VASP proteins control actin dynamics are unknown. We investigated how Ena/ VASP proteins regulate actin polymerization at actin filament barbed ends in vitro in the presence and absence of barbed end capping proteins. Recombinant His-tagged VASP increased the rate of actin polymerization in the presence of the barbed end cappers, heterodimeric capping protein (CP), CapG, and gelsolin-actin complex. Profilin enhanced the ability of VASP to protect barbed ends from capping by CP, and this required interactions of profilin with G-actin and VASP. The VASP EVH2 domain was sufficient to protect barbed ends from capping, and the F-actin and G-actin binding motifs within EVH2 were required. Phosphorylation by protein kinase A at sites within the VASP EVH2 domain regulated anticapping and F-actin bundling by VASP. We propose that Ena/ VASP proteins associate at or near actin filament barbed ends, promote actin assembly, and restrict the access of barbed end capping proteins.