Albee Alison J, Wiese Christiane
Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
Mol Biol Cell. 2008 Aug;19(8):3347-56. doi: 10.1091/mbc.e07-11-1204. Epub 2008 May 28.
Members of the transforming acidic coiled coil (TACC) protein family are emerging as important mitotic spindle assembly proteins in a variety of organisms. The molecular details of how TACC proteins function are unknown, but TACC proteins have been proposed to recruit microtubule-stabilizing proteins of the tumor overexpressed gene (TOG) family to the centrosome and to facilitate their loading onto newly emerging microtubules. Using Xenopus egg extracts and in vitro assays, we show that the Xenopus TACC protein maskin is required for centrosome function beyond recruiting the Xenopus TOG protein XMAP215. The conserved C-terminal TACC domain of maskin is both necessary and sufficient to restore centrosome function in maskin-depleted extracts, and we provide evidence that the N terminus of maskin inhibits the function of the TACC domain. Time-lapse video microscopy reveals that microtubule dynamics in Xenopus egg extracts are unaffected by maskin depletion. Our results provide direct experimental evidence of a role for maskin in centrosome function and suggest that maskin is required for microtubule anchoring at the centrosome.
转化酸性卷曲螺旋（TACC）蛋白家族成员正逐渐成为多种生物中重要的有丝分裂纺锤体组装蛋白。TACC蛋白发挥功能的分子细节尚不清楚，但有人提出TACC蛋白可将肿瘤过表达基因（TOG）家族的微管稳定蛋白招募至中心体，并促进它们加载到新出现的微管上。利用非洲爪蟾卵提取物和体外试验，我们发现非洲爪蟾TACC蛋白maskin除了招募非洲爪蟾TOG蛋白XMAP215外，对中心体功能也是必需的。maskin保守的C端TACC结构域对于恢复缺失maskin的提取物中的中心体功能既必要又充分，并且我们提供证据表明maskin的N端会抑制TACC结构域的功能。延时视频显微镜显示，非洲爪蟾卵提取物中的微管动力学不受maskin缺失的影响。我们的结果为maskin在中心体功能中的作用提供了直接的实验证据，并表明maskin是微管锚定在中心体所必需的。
