CRYSTAL-STRUCTURE OF CALMODULIN
CRYSTAL-STRUCTURE OF CALMODULIN
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DOI：
10.1016/0162-0134(86)80093-9
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发表时间：
1986-10-01
影响因子：
3.9
通讯作者：
WEISSMAN, LJ
中科院分区：
文献类型：
--
作者：
KRETSINGER, RH;RUDNICK, SE;WEISSMAN, LJ
钙调蛋白的晶体结构已确定为3.6.ANG。解决。在此分辨率下可以追踪多肽链。一些侧链已初步确定。使用测量到 1.65 ANG 的 X 射线衍射数据对结构进行细化。决议仍在继续。据 Babu 等人报道。 [1] 钙调蛋白约为 65 ANG。长 30 ANG。直径。同源结构域 1 和 2 通过局部双轴相关，如小白蛋白和肌钙蛋白 C，并形成分子的一端。域 3 和 4 形成另一端。结构域2的第二个α-螺旋和短结构域间区域与结构域3的第一螺旋连续，从而从残基67-93形成单个螺旋。该长螺旋的中心区域（残基 75-84）形成连接两对同源结构域的柄。不包括残基75-84，在手柄中，第1、2对侧链与第3、4对侧链最接近的位置是12.ANG。钙调蛋白中第1、2对与第3、4对侧链的空间关系与肌钙蛋白C中对应对的关系相似。然而，在肌钙蛋白C中，在长α-螺旋的手柄区域中存在另外三个残基，并且这两对大约是5.0 .ANG。距离更远。在钙调蛋白中的第 1、2 对的表面上，有一个延伸区域，具有来自结构域 1 和结构域 2 的许多疏水侧链。该疏水斑块由两个不同的阴离子侧链簇包围，一个从结构域 1 的第一个螺旋的起点开始，另一个在疏水表面的另一侧，从结构域 2 的第一个螺旋的起点开始。同样，第 3、4 对表面上的疏水斑块 由天冬氨酸和谷氨酸残基的两个簇包围。这些疏水表面中的一个或两个可以是钙调蛋白靶蛋白结合的位点。
The crystal structure of calmodulin has been determined to 3.6 .ANG. resolution. At this resolution the polypeptide chain can be traced. Some of the side chains have tentatively been identified. Refinement of the structure with x-ray diffraction data measured to 1.65 .ANG. resolution is continuing. As reported by Babu et al. [1] calmodulin is about 65 .ANG. long and 30 .ANG. in diameter. Homolog domains 1 and 2 are related by a local twofold axis, as in parvalbumin and in troponin C, and form one end of the molecule. Domains 3 and 4 form the other end. The second .alpha.-helix of domain 2 and a short interdomain region are continuous with the first helix of domain 3, thereby forming a single helix from residues 67-93. The central region, residues 75-84, of this long helix forms a handle connecting the two pairs of homolog domains. Exclusive of the residues, 75-84, in the handle the closet approach of side chains of pair 1, 2 to pair 3, 4 is 12 .ANG.. The spatial relationship of pair 1, 2 to pair 3, 4 is similar in calmodulin to the relationship of the corresponding pairs in troponin C. However, in troponin C there are three additional residues in the handle region of the long .alpha.-helix and the two pairs are about 5.0 .ANG. further apart. On the surface of pair 1, 2 in calmodulin there is one extended region with many hydrophobic side chains from both domain 1 and domain 2. This hydrophobic patch is bounded by two distinct clusters of anionic side chains, one from the beginning of the first helix of domain 1 and on the other side of the hydrophobic surface one from the beginning of the first helix of domain 2. Homologously, the hydrophobic patch on the surface of pair 3, 4 is bounded by two clusters of aspartate and glutamate residues. Either or both of these hydrophobic surfaces may be sites to which calmodulin target proteins bind.