Figure 1.

The APP–Fpn interaction structural motifs. A, schematic of domain organization of APP and its orthologues with APP secretase-processing sites indicated. The E1 and E2 elements comprise the APP ectodomain. B, the E2 domain and its five helical motifs. The FTP binding sequence (shown in C) is highlighted in red and is found at the C-terminal end of the αB helix. The αBαC domains were the recombinant proteins used in this report; in APP this domain consists of residues 318–408. The structure shown is from Protein Data Bank 3UMH. C, the FTP sequence in APP and APLP2 and the corresponding residues in APLP1. The FTP sequence is boxed with the residues targeted as FTP-specific in bold.