Wang C R, Castaño A R, Peterson P A, Slaughter C, Lindahl K F, Deisenhofer J
Department of Biochemistry, University of Texas Southwestern Medical Center Dallas 75235-9050, USA.
Cell. 1995 Aug 25;82(4):655-64. doi: 10.1016/0092-8674(95)90037-3.
H2-M3 is a class Ib MHC molecule of the mouse with a 10(4)-fold preference for binding N-formylated peptides. To elucidate the basis of this unusual specificity, we expressed and crystallized a soluble form of M3 with a formylated nonamer peptide, fMYFINILTL, and determined the structure by X-ray crystallography. M3, refined at 2.1 A resolution, resembles class la MHC molecules in its overall structure, but differs in the peptide-binding groove. The A pocket, which usually accommodates the free N-terminus of a bound peptide, is closed, and the peptide is shifted one residue, such that the P1 side chain is lodged in the B pocket. The formyl group is coordinated by His-9 and a bound water on the floor of the groove.
H2-M3是小鼠的一种Ib类主要组织相容性复合体（MHC）分子，对结合N-甲酰化肽具有10^4倍的偏好性。为了阐明这种异常特异性的基础，我们将M3的一种可溶形式与一种甲酰化九聚体肽fMYFINILTL一起表达并结晶，然后通过X射线晶体学确定其结构。以2.1埃分辨率精修后的M3，其整体结构类似于Ia类MHC分子，但在肽结合槽方面有所不同。通常容纳结合肽游离N端的A口袋是封闭的，肽移位了一个残基，使得P1侧链位于B口袋中。甲酰基由His-9和槽底部结合的一个水分子配位。
