Li P, Morris D L, Willcox B E, Steinle A, Spies T, Strong R K
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109 USA.
Nat Immunol. 2001 May;2(5):443-51. doi: 10.1038/87757.
The major histocompatibility complex (MHC) class I homolog, MICA, is a stress-inducible ligand for NKG2D, a C-type lectin-like activating immunoreceptor. The crystal structure of this ligand-receptor complex that we report here reveals an NKG2D homodimer bound to a MICA monomer in an interaction that is analogous to that seen in T cell receptor-MHC class I protein complexes. Similar surfaces on each NKG2D monomer interact with different surfaces on either the alpha1 or alpha2 domains of MICA. The binding interactions are large in area and highly complementary. The central section of the alpha2-domain helix, disordered in the structure of MICA alone, is ordered in the complex and forms part of the NKG2D interface. The extensive flexibility of the interdomain linker of MICA is shown by its altered conformation when crystallized alone or in complex with NKG2D.
主要组织相容性复合体（MHC）I类同源物MICA是NKG2D的应激诱导配体，NKG2D是一种C型凝集素样激活免疫受体。我们在此报道的这种配体-受体复合物的晶体结构揭示了一个NKG2D同二聚体与一个MICA单体结合，其相互作用类似于在T细胞受体-MHC I类蛋白复合物中看到的相互作用。每个NKG2D单体上的相似表面与MICA的α1或α2结构域上的不同表面相互作用。结合相互作用面积大且高度互补。单独的MICA结构中无序的α2结构域螺旋的中央部分在复合物中是有序的，并形成NKG2D界面的一部分。MICA结构域间连接子的广泛灵活性通过其单独结晶或与NKG2D复合结晶时构象的改变得以体现。
