Tabata Shigekazu, Kuroki Kimiko, Maita Nobuo, Wang Jing, Shiratori Ikuo, Arase Hisashi, Kohda Daisuke, Maenaka Katsumi
Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2008 Jan 1;64(Pt 1):44-6. doi: 10.1107/S1744309107065384. Epub 2007 Dec 20.
Human paired immunoglobulin-like (Ig-like) type 2 receptor alpha (PILRalpha) is a type I membrane protein that is mainly expressed in immune-related cells such as monocytes, granulocytes and dendritic cells. PILRalpha can suppress the functions of such immune cells because it has the immunoreceptor tyrosine-based inhibitory motif (ITIM) in the intracellular region, which recruits the phosphatase Src homology-2 (SH2) domain-containing protein tyrosine phosphatase 2 (SHP-2) to inhibit phosphorylations induced by activation signals. The extracellular region of human PILRalpha comprises one immunoglobulin superfamily V-set domain and a stalk region. The V-set domain (residues 13-131) of human PILRalpha was overexpressed in Escherichia coli as inclusion bodies, refolded by rapid dilution and purified. The PILRalpha protein was successfully crystallized at 293 K using the sitting-drop vapour-diffusion method. The crystals diffracted to 1.3 A resolution at SPring-8 BL41XU; they belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 40.4, b = 45.0, c = 56.9 A, and contain one molecule per asymmetric unit.
人配对免疫球蛋白样（Ig样）2型受体α（PILRα）是一种I型膜蛋白，主要表达于单核细胞、粒细胞和树突状细胞等免疫相关细胞中。PILRα可抑制此类免疫细胞的功能，因为其胞内区域含有免疫受体酪氨酸抑制基序（ITIM），该基序可招募含Src同源2（SH2）结构域的蛋白酪氨酸磷酸酶2（SHP-2）来抑制激活信号诱导的磷酸化。人PILRα的胞外区域由一个免疫球蛋白超家族V-set结构域和一个柄区组成。人PILRα的V-set结构域（第13至131位氨基酸残基）在大肠杆菌中作为包涵体过量表达，通过快速稀释进行重折叠并纯化。采用坐滴气相扩散法在293 K下成功获得了PILRα蛋白晶体。这些晶体在日本理化研究所的SPring-8 BL41XU光束线上衍射分辨率达到1.3 Å；它们属于空间群P2(1)2(1)2(1)，晶胞参数a = 40.4、b = 45.0、c = 56.9 Å，每个不对称单位包含一个分子。
