Structure-function analysis of Ia molecules: in-phase insertion mutagenesis of the amino-terminal domain of the E beta k polypeptide chain.
To identify which segments of the beta 1 domain of the E beta k polypeptide control T cell recognition of antigen, E beta genes were constructed with in-phase insertion mutations. Five independent mutants, with insertions mapping to positions 24, 50 and 93 of the E beta k polypeptide, were obtained. Cell lines expressing these mutated genes were analysed by microfluorometry using a panel of 20 anti-Ek monoclonal antibodies. None of the tested in-phase insertions has resulted in the loss of antibody binding sites. In striking contrast, mutations at position 93 and at a lesser level 50 were indicative of a crucial role of the corresponding regions in T-cell recognition, because they led to significant or complete loss of antigen-presenting function with all but one of the T hybridomas tested. These data are discussed with regard to a model of the foreign antigen binding site of Ia molecules.
Rebaï
N
N
Centre d'Immunologie INSERM-CNRS de Marseille-Luminy, France.
Letourneur
F
F
Shastri
N
N
Marchetto
S
S
Pierres
M
M
Malissen
B
B
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004251:DNA Transposable Elements; D005802:Genes, MHC Class II; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids; D013601:T-Lymphocytes / Q000276:immunology; D014162:Transfection
D004251:DNA Transposable Elements; D000949:Histocompatibility Antigens Class II; D046911:Macromolecular Substances