Kerkhoff Eugen
Institut für medizinsche Strahlenkunde und Zellforschung (MSZ), Universität Würzburg, Versbacher Strasse 5, 97078 Würzburg, Germany.
Trends Cell Biol. 2006 Sep;16(9):477-83. doi: 10.1016/j.tcb.2006.07.005. Epub 2006 Aug 9.
The initiation of actin polymerization from free monomers requires actin-nucleation factors. Spir proteins nucleate actin polymerization by a novel mechanism that is distinct from actin nucleation by the Arp2/3 complex or by formins. In vitro actin polymerization assays and electron microscopic data show that Spire nucleates actin polymerization by binding four actin monomers to a cluster of four Wiskott-Aldrich syndrome protein-homology domain 2 (WH2) domains in the central region of the proteins. Although the exact cell biological function and regulation of Spir proteins is still unknown, data from genetic studies in Drosophila, cell biological studies and protein interaction experiments have provided insight into the biology of these interesting and novel actin-nucleation factors and suggest a role in vesicle transport processes and in the coordination of cortical microtubule and actin filaments. Phosphorylation by mitogen-activated protein kinases and interaction with Rho GTPases have been proposed as regulatory mechanisms.
肌动蛋白从游离单体开始聚合需要肌动蛋白成核因子。Spir蛋白通过一种与Arp2/3复合体或formin介导的肌动蛋白成核不同的新机制来引发肌动蛋白聚合。体外肌动蛋白聚合分析和电子显微镜数据表明，Spire通过将四个肌动蛋白单体结合到蛋白质中央区域的四个威斯科特-奥尔德里奇综合征蛋白同源结构域2（WH2）结构域簇上，从而引发肌动蛋白聚合。尽管Spir蛋白确切的细胞生物学功能和调控机制仍不清楚，但来自果蝇遗传学研究、细胞生物学研究和蛋白质相互作用实验的数据，为这些有趣的新型肌动蛋白成核因子的生物学特性提供了深入了解，并表明它们在囊泡运输过程以及皮质微管和肌动蛋白丝的协调中发挥作用。有研究提出，丝裂原活化蛋白激酶的磷酸化作用以及与Rho GTP酶的相互作用是其调控机制。
