Department of Biochemistry, Molecular and Structural Biology and Centre for Protein and Structure Production, Jozef Stefan Institute, Ljubljana, Slovenia.
FEBS Lett. 2012 May 7;586(9):1318-24. doi: 10.1016/j.febslet.2012.03.038. Epub 2012 Mar 27.
Major histocompatibility class (MHC) II molecules are essential for running adaptive immune response. They are produced in the ER and targeted to late endosomes with the help of invariant chain (Ii) trimers. Ii trimerization may be induced by the Ii TM domain. To enable mechanistic and structural studies of MHC class II-Ii assembly, soluble forms of the complexes were expressed. We show that Ii trimerizes in the absence of the transmembrane part, prior to binding of α/β chains. The biochemical analysis supports the suggestion that the MHC class II-Ii complexes are not necessarily trimers of trimers, but that the Ii trimer can also be occupied by one or two MHC class II complexes.
主要组织相容性复合体 (MHC) II 类分子是进行适应性免疫反应所必需的。它们在 ER 中产生，并在不变链 (Ii) 三聚体的帮助下靶向晚期内体。Ii 三聚体化可能由 IiTM 结构域诱导。为了能够对 MHC Ⅱ类-Ii 组装进行机制和结构研究，表达了这些复合物的可溶性形式。我们表明，Ii 在结合 α/β 链之前就会在没有跨膜部分的情况下三聚化。生化分析支持这样的观点，即 MHC Ⅱ类-Ii 复合物不一定是三聚体的三聚体，而是 Ii 三聚体也可以被一个或两个 MHC Ⅱ类复合物占据。
