 The E2 domain is the largest subdomain of APLP2 and consists of six alpha-helixes.The N-terminal double stranded coiled coil structure of the first monomer of E2 packs against the C-terminal triple stranded coiled coil structure of the second monomer.The BPTI/Kunitz inhibitor domain (residues 306-364) is ‘Cys-rich’ and is capable of inhibiting several proteases.