Schmid M F, Jakana J, Matsudaira P, Chiu W
Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, Texas 77030, USA.
Biophys J. 1995 Apr;68(4 Suppl):8S-11S.
The acrosomal bundle of Limulus sperm was imaged by electron cryomicroscopy, and the three-dimensional structure of a filament computationally isolated from the bundle was determined by helical image reconstruction. The actin model of Holmes was fit into the map, and its interactions with scruin, the actin-binding and cross-linking protein, were studied. Scruin binds to two consecutive actins along the helix via subdomains 1 and 3. These interactions involve helix-loop-beta motifs that are present in both actin subdomains (in different monomers) in positions available for binding by the same scruin molecule as it wraps around the actin. Taking first the structural motif homology and then looking for sequence pattern similarities, a stretch of 12 out of 20 matches in hydrophobicity is found. Scruin itself has been found to have an internal tandem homology.
通过电子冷冻显微镜对鲎精子的顶体束进行成像，并通过螺旋图像重建确定从该束中计算分离出的细丝的三维结构。将福尔摩斯的肌动蛋白模型拟合到图谱中，并研究其与肌动蛋白结合和交联蛋白scruin的相互作用。Scruin通过亚结构域1和3沿着螺旋与两个连续的肌动蛋白结合。这些相互作用涉及肌动蛋白亚结构域（在不同单体中）中存在的螺旋-环-β基序，当scruin分子围绕肌动蛋白缠绕时，这些基序处于可被同一scruin分子结合的位置。首先考虑结构基序同源性，然后寻找序列模式相似性，发现在20个匹配中有12个在疏水性上相似。已发现scruin本身具有内部串联同源性。
