The I-A beta b region (65-85) is a binding site for the superantigen, staphylococcal enterotoxin A.
Ia antigen is a receptor for the superantigen staphylococcal enterotoxin A (SEA). Peptides I-A beta b(30-60), I-A beta b(50-70), I-A beta b(65-85), and I-A beta b(80-100) of the MHC class II antigen beta chain on mouse (H-2b) accessory cells were synthesized. Only I-A beta b(65-85) inhibited SEA binding to the mouse B-cell lymphoma line, A20 (H-2d) and the human Burkitt's lymphoma line, Raji (HLA-DR). The I-A beta b(65-85) sequence is a predicted alpha-helix along the hypothetical antigen binding cleft of the Ia molecule. I-A beta b(65-85) also directly and specifically bound both the intact SEA molecule and its Ia binding site, represented by the peptide SEA(1-45). The results suggest that I-A beta b region (65-85) is a necessary site for Ia molecular interaction with the superantigen SEA. Further, the data suggest that the same helical region of other Ia antigens binds SEA irrespective of haplotype and species.
Russell
J K
JK
Department of Microbiology and Cell Science, University of Florida, Gainesville 32611.
Pontzer
C H
CH
Johnson
H M
HM
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D004768:Enterotoxins / Q000494:pharmacology*; D005453:Fluorescence; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D004768:Enterotoxins; D000949:Histocompatibility Antigens Class II; D011956:Receptors, Cell Surface; C026066:enterotoxin A, Staphylococcal