Gusev N B
Department of Biochemistry, School of Biology and School of Fundamental Medicine, Lomonosov Moscow State University, Moscow, 119899, Russia.
Biochemistry (Mosc). 2001 Oct;66(10):1112-21. doi: 10.1023/a:1012480829618.
The interaction of caldesmon with different Ca2+-binding proteins has been analyzed, and it is supposed that one of the conformers of calmodulin might be an endogenous regulator of caldesmon. The arrangement of caldesmon and Ca2+-binding proteins within their complexes has been analyzed by different methods. The central helix of calmodulin is supposed to be located near the single Cys residue in the C-terminal domain of caldesmon. The N-terminal globular domain of calmodulin interacts with sites A and B' of caldesmon, whereas the C-terminal globular domain of calmodulin binds to site B of caldesmon. The complex of calmodulin and caldesmon is very flexible; therefore, both parallel and antiparallel orientation of polypeptide chains of the two proteins is possible in experiments with short fragments of caldesmon and calmodulin. The length, flexibility, and charge of the central helix of calmodulin play an important role in its interaction with caldesmon. Phosphorylation of caldesmon by different protein kinases in vitro has been analyzed. It was shown that phosphorylation catalyzed by casein kinase II of sites located in the N-terminal domain decreases the interaction of caldesmon with myosin and tropomyosin. Caldesmon and calponin may interact with phospholipids. The sites involved in the interaction of these actin-binding proteins with phospholipids have been mapped. It is supposed that the interaction of calponin and caldesmon with phospholipids may play a role in the formation of cytoskeleton. Calponin interacts with 90-kD heat shock protein (hsp90) that may be involved in transportation of calponin and its proper interaction with different elements of cytoskeleton. Calponin, filamin, and alpha-actinin can simultaneously interact with actin filaments. Simultaneous binding of two actin-binding proteins affects the structure of actin bundles and their mechanical properties and may be of great importance in formation of different elements of cytoskeleton.
已分析了钙调蛋白与不同钙结合蛋白的相互作用，并且推测钙调蛋白的一种构象异构体可能是钙调蛋白的内源性调节剂。已通过不同方法分析了钙调蛋白和钙结合蛋白在其复合物中的排列。钙调蛋白的中央螺旋被认为位于钙调蛋白C末端结构域中的单个半胱氨酸残基附近。钙调蛋白的N末端球状结构域与钙调蛋白的A和B'位点相互作用，而钙调蛋白的C末端球状结构域与钙调蛋白的B位点结合。钙调蛋白和钙调蛋白的复合物非常灵活；因此，在使用钙调蛋白和钙调蛋白的短片段进行的实验中，两种蛋白质的多肽链的平行和反平行取向都是可能的。钙调蛋白中央螺旋的长度、灵活性和电荷在其与钙调蛋白的相互作用中起重要作用。已分析了不同蛋白激酶在体外对钙调蛋白的磷酸化作用。结果表明，酪蛋白激酶II催化的位于N末端结构域的位点的磷酸化降低了钙调蛋白与肌球蛋白和原肌球蛋白的相互作用。钙调蛋白和钙调磷酸蛋白可能与磷脂相互作用。已确定了这些肌动蛋白结合蛋白与磷脂相互作用所涉及的位点。推测钙调磷酸蛋白和钙调蛋白与磷脂的相互作用可能在细胞骨架的形成中起作用。钙调磷酸蛋白与90-kD热休克蛋白（hsp90）相互作用，hsp90可能参与钙调磷酸蛋白的运输及其与细胞骨架不同成分的正确相互作用。钙调磷酸蛋白、细丝蛋白和α-辅肌动蛋白可以同时与肌动蛋白丝相互作用。两种肌动蛋白结合蛋白的同时结合会影响肌动蛋白束的结构及其机械性能，并且可能在细胞骨架不同成分的形成中具有重要意义。
