Expression And Purification Study Of Gamma-Secretase Associated With Alzheimer's Disease

Alzheimer's disease is a chronic neurodegenerative disease, highly prevalent in the elders. However AD may be closely linked with the genetic factors that caused the disease in the earlier life. It is characterized by amyloid-? peptides(A?) deposit formed of senile plaques and neurofibrillary tangles, which can lead to nerve cell loss.A? is formed from amyloid-? precursor protein(APP) throughout three protease activities. Gamma-secretase plays an important role in the APP cleavage, generating A?40/A?42. Thus, gaining a detailed structure understanding help reveal the mechanism how ?-secretase processes APP and the information is critically important for medicine design for AD cure.Gamma-secretase complex belongs to intramembrane-cleaving proteases family(I-CHIPs) with 19 transmembrane domains. It is composed of four components: presenilin(PS), nicastrin(NCT), PEN2 and Aph-1a. In this study, we successfully expressed the components and complex by mainly applying bac-to-bac baculovirus insect cells and mammalian cells expression system. Due to the hydrophobic domains of membrane proteins, we attached our importance on detergent screen for solubilizing the membrane fraction. Then, we extracted and purified the components with optimized detergent. From this purification procedure, we obtained the NCT with high purity and deglycosylated the target protein. Besides, we obtained the other components and complex. These results could lay a solid foundation for the study on protein-protein interaction and structure of ?-secretase complex.