Dissociation of the Peptide-MHC Class I Complex Limits the Binding Rate of Exogenous Peptide

David M. Ojcius*, Jean Pierre Abastado, Armanda Casrouge, Estelle Mottez, Lucien Cabanie, Philippe Kourilsky

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

26 Scopus citations


Soluble, single-chain molecules for two MHC class I alleles, H-2Kd and H-2Kb, were used to analyze the kinetics of antigenic peptide binding to MHC. After MHC preloading with radiolabeled or fluorescent peptides, the observed rate of MHC-peptide complex dissociation increased after addition of an excess of unlabeled competitor peptide. Although exogenous peptides conforming to the allele-specific motif were required for the enhanced complex dissociation to occur, the dissociation rate of the complex was independent of exogenous peptide concentration. Similarly, the association rate of exogenous peptides was independent of concentration, reflecting the presence of low affinity peptides in the binding sites of the recombinant MHC proteins; the sequences of these endogenous peptides conform to the consensus motif for the MHC allele studied. Finally, the association rate of exogenous peptide decreased when MHC molecules were preloaded with high affinity peptides, and the binding of labeled high affinity peptide to isolated recombinant MHC was faster than the subsequent dissociation observed in the presence of competitor peptide. Taken together, these results imply that the rate of exogenous peptide binding is limited by the dissociation rate of the previously bound peptides.

Original languageEnglish
Pages (from-to)6020-6026
Number of pages7
JournalJournal of Immunology
Issue number11
StatePublished - 01 12 1993
Externally publishedYes


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