钙不依赖性钙调素结合蛋白的研究进展

ApoCalmodulin and Ca^(2+)-independent Calmodulin-binding Proteins

钙调素是普遍存在于真核生物细胞中、发挥多种生物学调控作用的信号组分.钙调素不仅在有Ca2+情况下通过与钙依赖性钙调素结合蛋白作用而传递信号,也能在相对无Ca2+条件下直接结合钙不依赖性钙调素结合蛋白而传递信号.综述了无钙离子结合钙调素及钙不依赖性钙调素结合蛋白的结构特性、钙不依赖性钙调素结合蛋白的种类及其可能的生物学作用,这将有助于我们深入认识钙调素介导信号途径的特异性、复杂性和多样性.

Caimodulin （CAM） is ubiquitous, multifunctional calcium （Ca^2＋） sensor that exists in all eukaryotes. As it has no enzymatic activity, CAM transmits the Ca^2＋ signal by interacting with CAM-binding proteins （CaMBPs） to function in cellular regulation. In recent years, it has been found that CaM not only signals in the presence of Ca^2＋, it can also directly bind to target proteins as ApoCAM. Ca^2＋-independent CAM-binding proteins （ApoCaMBPs） is also an important way to elucidate the mechanism of CaM functions. Recent progresses in studies on animal and plant ApoCaMBPs were summarized. ApoCAM differs from Ca^2＋-CAM in its tertiary structure. It binds target proteins differently, utilizing different binding motifs such as the IQ motif, noncontiguous binding sites and others. The ApoCaMBPs are a diverse group of proteins including enzymes, transcription activators, as well as cytoskeletal and other membrane proteins, including receptors and ion channels. The overall picture that emerges is that CAM cycles between its Ca^2＋-bound and Ca^2＋-free states and in each state binds to different proteins and performs essential functions. Although much of the research focus has been on the roles of Ca^2＋-CaM binding proteins, the roles of ApoCaMBPs are equally vital but less well understood. Researches on ApoCaM and its binding proteins will make us understand the variety of CaM signaling pathway.