University of Illinois at Chicago, Department of Biochemistry and Molecular Genetics, 900 S. Ashland Ave., MBRB 1170, Chicago, IL 60607, USA.
Biochem Biophys Res Commun. 2010 Feb 19;392(4):490-4. doi: 10.1016/j.bbrc.2010.01.046. Epub 2010 Jan 15.
The spectrin-based cytoskeleton is critical for cell stability, membrane organization and membrane protein trafficking. At its core is the high-affinity complex between beta-spectrin and ankyrin. Defects in either of these proteins may cause hemolytic disease, developmental disorders, neurologic disease, and cancer. Crystal structures of the minimal recognition motifs of ankyrin and beta-spectrin have been determined and distinct recognition mechanisms proposed. One focused on the complementary surface charges of the minimal recognition motifs, whereas the other identified an unusual kink between beta-spectrin repeats and suggested a conformation-sensitive binding surface. Using isothermal titration calorimetry and site-directed mutagenesis, we demonstrate the primacy of the inter-repeat kink as the critical determinant underlying spectrin's ankyrin affinity. The clinical implications of this are discussed in light of recognized linker mutations and polymorphisms in the beta-spectrins.
基于血影蛋白的细胞骨架对于细胞稳定性、膜组织和膜蛋白运输至关重要。其核心是β- spectrin 和 ankyrin 之间的高亲和力复合物。这两种蛋白质中的任何一种缺陷都可能导致溶血性疾病、发育障碍、神经疾病和癌症。ankyrin 和 β-spectrin 的最小识别基序的晶体结构已经确定，并提出了不同的识别机制。一种机制集中在最小识别基序的互补表面电荷上，而另一种机制则确定了β-spectrin 重复之间的不寻常扭曲，并提出了一个构象敏感的结合表面。使用等温滴定量热法和定点突变，我们证明了重复之间的扭曲作为 spectrin 与 ankyrin 亲和力的关键决定因素的首要地位。鉴于β-spectrin 中的公认连接子突变和多态性，讨论了这一发现的临床意义。
