Spang A, Grein K, Schiebel E
Max-Planck Institut für Biochemie, Genzentrum, Martinsried, Germany.
J Cell Sci. 1996 Sep;109 ( Pt 9):2229-37. doi: 10.1242/jcs.109.9.2229.
Yeast calmodulin (CaM) was found to be localized to the microtubule organizing centre, the spindle pole body. The spindle pole body is a multi-layered structure consisting of outer, central and inner plaques. In this paper, we report that a fraction of CaM is in association with the central plaque of the spindle pole body. This localization is dependent on the calmodulin-binding site of another spindle pole body component, Spc110p, which serves as a spacer connecting the inner plaque with the central plaque. Since the CaM-binding site of Spc110p is located near the carboxy terminus, Spc110p-dependent localization of calmodulin defines the orientation of Spc110p with the carboxy terminus towards the central plaque and the amino terminus towards the inner plaque. This orientation of Spc110p was confirmed using antibodies specific for the amino-terminal end of Spc110p, which predominantly labelled the inner plaque. In addition, synthetic peptides corresponding to the calmodulin-binding site of Spc110p bound to calmodulin with a Kd in the nanomolar range and nearly independent of Ca2+.
酵母钙调蛋白（CaM）被发现定位于微管组织中心，即纺锤极体。纺锤极体是一种由外层、中层和内层板组成的多层结构。在本文中，我们报道了一部分CaM与纺锤极体的中层板相关联。这种定位依赖于纺锤极体另一个组分Spc110p的钙调蛋白结合位点，Spc110p作为连接内层板和中层板的间隔物。由于Spc110p的CaM结合位点位于羧基末端附近，钙调蛋白依赖于Spc110p的定位确定了Spc110p的方向，即羧基末端朝向中层板，氨基末端朝向内层板。使用针对Spc110p氨基末端的特异性抗体证实了Spc110p的这种方向，该抗体主要标记内层板。此外，与Spc110p的钙调蛋白结合位点对应的合成肽以纳摩尔范围内的解离常数（Kd）与钙调蛋白结合，且几乎不依赖于Ca2+。
