ovalbumin and formic-acid

We previously established that H-2M3a, the H chain of the maternally transmitted Ag (Mta), is specialized for presentation of N-formylated peptides. We hypothesized that the N-formyl group might prevent or limit the presentation of peptide Ag by H-2K and H-2D molecules. We now show by Mta- and OVA-specific CTL assays, peptide competition, and immunofluorescence analyses that N-formyl modification of four antigenic peptides inhibited their binding by either H-2Kb (OVAMet258-264, VSVNP52-59, and SVNP324-332) or H2-Db (SVNP324-332, and IVNP366-374). In contrast, N-formyl-OVAMet258-264 did bind to H2-M3a. The data imply lack of an N-formyl-binding pocket in classical MHC class I molecules and are consistent with a specialized role for H2-M3a in presentation of N-formylated peptides such as derived from intracellular prokaryotic parasites.

Topics: Alkylation; Amino Acid Sequence; Animals; Antigens, Viral; Cells, Cultured; Cytotoxicity, Immunologic; Epitopes; Formates; H-2 Antigens; In Vitro Techniques; Mice; Molecular Sequence Data; Nucleocapsid Proteins; Nucleoproteins; Ovalbumin; Parainfluenza Virus 1, Human; Peptides; Protein Binding; Structure-Activity Relationship; T-Lymphocytes, Cytotoxic; Vesicular stomatitis Indiana virus; Viral Core Proteins