Solution structure of human CTLA-4 and delineation of a CD80/CD86 binding site conserved in CD28.
Metzler W.J., Bajorath J., Fenderson W., Shaw S.Y., Constantine K.L., Naemura J., Leytze G., Peach R.J., Lavoie T.B., Mueller L., Linsley P.S.
The structure of human CTLA-4 reveals that residues Met 99, Tyr 100 and Tyr 104 of the M99YPPPY104 motif are adjacent to a patch of charged surface residues on the A'GFCC' face of the protein. Mutation of these residues, which are conserved in the CTLA-4/CD28 family, significantly reduces binding to CD80 and/or CD86, implicating this patch as a ligand binding site.