NCIt definition : A protein complex that plays a role in the intramembrane cleavage of integral proteins
such as Notch receptors and amyloid beta A4 protein.;
NCIt note : The components required for the enzymatic activity of gamma secretase are a homodimer
of presenilin (PSEN1 or PSEN2), nicastrin (NCSTN), APH1 (APH1A or APH1B) and PEN2.
The proteolytic activity appears to be mediated by presenilin, while the other proteins
are required for both stabilization of the active form of presenilin and localization
of the complex.;