Secondary structure analyses of pY sequences suggest that pY epitopes are commonly embedded in 3D epitopes containing a helix or sheet structure. (A) Schematic illustration of linear and three-dimensional (3D) pY motifs in the receptor proteins in a cell. (B) Secondary structure analysis of 1501 pY sites using the DSSP algorithm based on available PDB structures. (C) Secondary structure prediction of 6063 pY sequences using the GOR algorithm. Position 0 is the pY residue; positions −7 to −1 or 1 to 7 are the seven residues upstream or downstream of the pY motif. H, helices (3,4,5- turn helix); E, strand (ß-sheet, ß-bridge); C, loop (bend, turn, coil).