. "Dimerization of A??PP at the ectodomain is mainly regulated by its E1 growth factor like domain that possesses a loop region of disulphide bonds [30], its E1 metal-binding domain that coordinates metal ions such as copper and zinc, and its E2 collagen binding domain that adheres to extracellular matrix molecules such as heparin, collagen [28,31,32] and possibly N-cadherin [33]." . . . .