A hypothetical model of the foreign antigen binding site of class II histocompatibility molecules.
Class II and class I histocompatibility molecules allow T cells to recognize 'processed' polypeptide antigens. The two polypeptide chains of class II molecules, alpha and beta, are each composed of two domains (for review see ref. 6); the N-terminal domains of each, alpha 1 and beta 1, are highly polymorphic and appear responsible for binding peptides at what appears to be a single site and for being recognized by MHC-restricted antigen-specific T cells. Recently, the three-dimensional structure of the foreign antigen binding site of a class I histocompatibility antigen has been described. Because a crystal structure of a class II molecule is not available, we have sought evidence in class II molecules for the structural features observed in the class I binding site by comparing the patterns of conserved and polymorphic residues of twenty-six class I and fifty-four class II amino acid sequences. The hypothetical class II foreign-antigen binding site we present is consistent with mutation experiments and provides a structural framework for proposing peptide binding models to help understand recent peptide binding data.
Brown
J H
JH
Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138.
Jardetzky
T
T
Saper
M A
MA
Samraoui
B
B
Bjorkman
P J
PJ
Wiley
D C
DC
D000911:Antibodies, Monoclonal; D001665:Binding Sites; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D000949:Histocompatibility Antigens Class II; D008213:Lymphocyte Activation; D008958:Models, Molecular; D013601:T-Lymphocytes / Q000276:immunology
D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II