Structure of importin-beta bound to the IBB domain of importin-alpha.
Structure of importin-beta bound to the IBB domain of importin-alpha.
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DOI：
10.2210/pdb1qgr/pdb
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发表时间：
1999-05
期刊：
影响因子：
64.8
通讯作者：
G. Cingolani;C. Petosa;K. Weis;C. Müller
中科院分区：
文献类型：
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作者：
G. Cingolani;C. Petosa;K. Weis;C. Müller
携带经典核定位信号的细胞质蛋白与importin- α和importin- β的异源二聚体（也称为核柔蛋白- α和- β）结合进入细胞核。这种异二聚体的形成涉及importin- α的importin- β结合（IBB）结构域，这是一个高度碱性的氨基末端区域，大约有40个氨基酸残基。在这里，我们报告了人类importin- β结合importin- α的IBB结构域的晶体结构，在2.5 A和2.3 A分辨率下以两种晶体形式测定。Importin-beta由19个串联重复的HEAT基序组成，紧密包裹在IBB结构域周围。这种结合涉及进口蛋白- β的两个独立区域，识别IBB结构域结构上不同的部分：氨基末端延伸部分和羧基末端螺旋。该结构表明，当importin- β结合或释放IBB结构域时，会发生显著的构象变化，并提示在核进入时如何实现importin- α / β异二聚体的解离。
Cytosolic proteins bearing a classical nuclear localization signal enter the nucleus bound to a heterodimer of importin-alpha and importin-beta (also called karyopherin-alpha and -beta). The formation of this heterodimer involves the importin-beta-binding (IBB) domain of importin-alpha, a highly basic amino-terminal region of roughly 40 amino-acid residues. Here we report the crystal structure of human importin-beta bound to the IBB domain of importin-alpha, determined at 2.5 A and 2.3 A resolution in two crystal forms. Importin-beta consists of 19 tandemly repeated HEAT motifs and wraps intimately around the IBB domain. The association involves two separate regions of importin-beta, recognizing structurally distinct parts of the IBB domain: an amino-terminal extended moiety and a carboxy-terminal helix. The structure indicates that significant conformational changes occur when importin-beta binds or releases the IBB domain domain and suggests how dissociation of the importin-alpha/beta heterodimer may be achieved upon nuclear entry.