The role of Ia in the formation of a T cell antigen-recognition complex.
We have evaluated the ability of a peptide-specific, I-Ak-restricted murine T hybridoma to bind its Ag in the presence and absence of class II MHC molecules. The restricting Ia molecule, when supplied as a plasma membrane preparation of I-Ak-expressing APC, specifically increases the avidity of the Ag-binding complex by lengthening its t1/2, without affecting the rate at which the complex is formed. Experiments using mutated I-Ak molecules indicate that the ability of a mutant Ia species to present Ag is distinct from its ability to stabilize the Ag-recognition complex, suggesting that T cell stimulation depends not only upon stabilization of Ag-TCR-Ia complexes, but also upon distinct Ia-influenced conformational signals.
Esch
T R
TR
Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor 48109.
McKean
D J
DJ
Thomas
D W
DW
D000595:Amino Acid Sequence; D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology; D005345:Fibrinopeptide B / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000502:physiology*; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D013329:Structure-Activity Relationship; D013601:T-Lymphocytes / Q000276:immunology*
D000949:Histocompatibility Antigens Class II; D046911:Macromolecular Substances; D011948:Receptors, Antigen, T-Cell; D005345:Fibrinopeptide B