Candidate gamma-secretases in the generation of the carboxyl terminus of the Alzheimer's disease beta-A4 amyloid: possible involvement of cathepsin D

The beta- and gamma-secretases are unidentified endoproteases that cleave the amino- and carboxyl termini, respectively, of the amyloid precursor protein (APP) to yield beta A4 amyloid peptide, the main component of cerebrovascular plaques that cause Alzheimer's disease. A study was conducted to determine if elastase, collagenase or cathepsin D cleaves the carboxyl terminus of APP. The results indicate that an enzyme similar to cathepsin D could be the gamma-secretase.