N-glycosylation of human nicastrin is required for interaction with the lectins from the secretory pathway calnexin and ERGIC-53
Morais, Vanessa Brito, Catarina Pijak, Donald S Crystal, Adam S Fortna, Ryan R Li, Tong Wong, Phil C Doms, Robert W Costa, Julia # ×
Biochimica et Biophysica Acta. Molecular Basis of Disease vol:1762 issue:9 pages:802-810
The gamma-secretase complex, composed of four non-covalently bound transmembrane proteins Presenilin, Nicastrin (NCT), APH-1 and PEN-2, is responsible for the intramembranous cleavage of amyloid precursor protein (APP), Notch and several other type 1 transmembrane proteins. gamma-Secretase cleavage of APP releases the A beta peptides, which form the amyloid plaques characteristic of Alzheimer's disease brains, and cleavage of Notch releases an intracellular signalling peptide that is critical for numerous developmental processes. NCT, a type I membrane protein, is the only protein within the complex that is glycosylated. The importance of these glycosylation sites is not fully understood. Here, we have observed that NCT N-linked oligosaccharides mediated specific interactions with the secretory pathway lectins calnexin and ERGIC-53. In order to investigate the role played by N-glycosylation, mutation of each site was performed. All hNCT mutants interacted with calnexin and ERGIC-53, indicating that the association was not mediated by any single Ar-glycosylation site. Moreover, the interaction with ERGIC-53 still occurred in PS1/2 double knockout cells as detected in immunoprecipitation as well as confocal immuno fluorescence microscopy studies, which indicated that NCT interacted with ERGIC-53 prior to its association with the active gamma-secretase complex. (c) 2006 Elsevier B.V. All rights reserved.