Mäler L, Blankenship J, Rance M, Chazin W J
Department of Molecular Biology (MB9), The Scripps Research Institute, 10550 North Torrey Pines Road., La Jolla, California 92037, USA.
Nat Struct Biol. 2000 Mar;7(3):245-50. doi: 10.1038/73369.
The cooperative binding of Ca2+ ions is an essential functional property of the EF-hand family of Ca2+-binding proteins. To understand how these proteins function, it is essential to characterize intermediate binding states in addition to the apo- and holo-proteins. The three-dimensional solution structure and fast time scale internal motional dynamics of the backbone have been determined for the half-saturated state of the N56A mutant of calbindin D9k with Ca2+ bound only in the N-terminal site. The extent of conformational reorganization and a loss of flexibility in the C-terminal EF-hand upon binding of an ion in the N-terminal EF-hand provide clear evidence of the importance of site-site interactions in this family of proteins, and demonstrates the strength of long-range effects in the cooperative EF-hand Ca2+-binding domain.
Ca2+离子的协同结合是Ca2+结合蛋白EF手型家族的一项基本功能特性。为了解这些蛋白质的功能，除了脱辅基蛋白和全蛋白外，表征中间结合状态也至关重要。已确定仅在N端位点结合Ca2+的钙结合蛋白D9k的N56A突变体半饱和状态下的三维溶液结构以及主链的快速时间尺度内部运动动力学。当N端EF手型结合离子时，C端EF手型的构象重组程度和灵活性丧失，这清楚地证明了位点间相互作用在该蛋白质家族中的重要性，并证明了协同EF手型Ca2+结合结构域中远程效应的强度。
