期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1990
卷号：87
期号：18
页码：7170-7174
DOI：10.1073/pnas.87.18.7170
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The binding of a chicken ovalbumin peptide (residues 323-339), Ova-(323-339), to I-Ad molecules was investigated in vitro and in vivo. By using antigenic peptides labeled either with a hapten or with fluorescein, complexes formed in vitro between I-Ad and antigenic peptides were detected by Western blot analysis with an antibody recognizing the hapten 7-nitrobenzo-2-oxa-1,3-diazole and by scanning gels for fluorescence emitted by fluoresceinated peptide. Both techniques reveal that Ova-(323-339) binds not only to I-Ad alpha/beta heterodimers and separated alpha and beta chains but also to complexes of higher molecular mass. Additional analysis shows that one of these additional complexes contains I-Ad heterodimers, antigenic peptides, and also invariant chain. To explore the physiological role of these complexes, cells were incubated with haptenated peptide and the I-Ad-peptide complexes formed in vivo were purified by affinity chromatography using hapten-specific antibody. The complexes formed migrate with a significantly higher apparent molecular mass than the alpha/beta heterodimers. A band at 180 kDa contained the alpha/beta heterodimer, the antigenic peptide, and the invariant chain. These results show that in vivo high molecular mass complexes formed by the I-Ad heterodimer and the invariant chain bind antigenic peptides.
