Sette A, Ceman S, Kubo R T, Sakaguchi K, Appella E, Hunt D F, Davis T A, Michel H, Shabanowitz J, Rudersdorf R
Laboratory of Genetics, University of Wisconsin, Madison 53706.
Science. 1992 Dec 11;258(5089):1801-4. doi: 10.1126/science.1465617.
Class II major histocompatibility complexes bind peptides in an endosome-like compartment. When the class II null cell line 721.174 was transfected with class II DR3 genes, DR molecules were produced in normal amounts. However, the DR molecules were abnormally conformed and unstable because deletion of an antigen-processing gene had impaired intracellular formation of most class II-peptide complexes. Yet, 70 percent of the DR molecules still bore peptides, 80 percent of which were 21- to 24-amino acid fragments of the class II-associated invariant chain. These peptides were rare on DR3 from control cells. Thus, a defect in the main antigen-processing pathway revealed a process in which DR molecules bind long peptides derived from proteins present in the same compartment.
II类主要组织相容性复合体在内体样区室中结合肽段。当II类基因缺失的细胞系721.174用II类DR3基因转染时，DR分子以正常量产生。然而，由于一个抗原加工基因的缺失损害了大多数II类 - 肽复合物的细胞内形成，DR分子的构象异常且不稳定。然而，70%的DR分子仍然带有肽段，其中80%是II类相关恒定链的21至24个氨基酸片段。这些肽段在对照细胞的DR3上很少见。因此，主要抗原加工途径中的缺陷揭示了一个过程，即DR分子结合来自同一区室中存在的蛋白质的长肽段。
