Role of the β-subunit arginine/lysine finger in integrin heterodimer formation and function
Role of the β-subunit arginine/lysine finger in integrin heterodimer formation and function
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DOI：
10.4049/jimmunol.180.3.1713
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发表时间：
2008-02-01
影响因子：
4.4
通讯作者：
Arnaout, M. Amin
中科院分区：
文献类型：
--
作者：
Gupta, Vineet;Alonso, Jose Luis;Arnaout, M. Amin
整合素α β异二聚体的形成对于细胞表面表达和功能至关重要。在α β界面的核心是来自β亚基的保守Arg/Lys“指状物”，其插入由α亚基中的两层芳香残基形成的杯状“笼”中。我们分别评估了该残基在缺乏α A和含有α A的整合素α V β 3和α M β 2（CD 11b/CD 18）中异源二聚体形成中的作用。将β 3的Arg 261突变为Ala或Glu;将β 2的相应Lys 252突变为Ala、Arg、Glu、Asp或Phe;并通过ELISA和.在用编码α-和β-亚基的质粒共转染的HEK 293细胞中进行免疫沉淀。Arg 261 Glu（而不是Arg 261 Ala）取代显著损害细胞表面表达和α V β 3异二聚体形成。虽然Lys 252 Arg和Lys 252 Ala在较小程度上耐受良好，但其余取代均显著降低了细胞表面表达和CD 11b/CD 18的异源二聚体形成。Lys 252 Arg和Lys 252 Ala整合素异二聚体显示与生理配体iC 3b结合的显著增加。这些数据表明了一个重要的作用的精氨酸/赖氨酸指形成一个稳定的整合素异源二聚体，并建议，在这个残基的细微变化影响的活化状态的整合素。
Formation of the integrin alpha beta heterodimer is essential for cell surface expression and function. At the core of the alpha beta interface is a conserved Arg/Lys "finger" from the beta-subunit that inserts into a cup-like "cage" formed of two layers of aromatic residues in the alpha-subunit. We evaluated the role of this residue in heterodimer formation in an alpha A-lacking and an alpha A-containing integrin alpha V beta 3 and alpha M beta 2 (CD11b/CD18), respectively. Arg261 of beta 3 was mutated to Ala or Glu; the corresponding Lys252 of beta 2 was mutated to Ala, Arg, Glu, Asp, or Phe; and the effects on heterodimer formation in each integrin examined by ELISA and. immunoprecipitation in HEK 293 cells cotransfected with plasmids encoding the alpha- and beta-subunits. The Arg261Glu (but not Arg261Ala) substitution significantly impaired cell surface expression and heterodimer formation of alpha V beta 3. Although Lys252Arg, and to a lesser extent Lys252Ala, were well tolerated, each of the remaining substitutions markedly reduced cell surface expression and heterodimer formation of CD11b/CD18. Lys252Arg and Lys252Ala integrin heterodimers displayed a significant increase in binding to the physiologic ligand iC3b. These data demonstrate an important role of the Arg/Lys finger in formation of a stable integrin heterodimer, and suggest that subtle changes at this residue affect the activation state of the integrin.