N-glycosylation of human nicastrin is required for interaction with the lectins from the secretory pathway calnexin and ERGIC-53.
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 I transmembrane proteins. gamma-Secretase cleavage of APP releases the Abeta 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 N-glycosylation site. Moreover, the interaction with ERGIC-53 still occurred in PS1/2 double knockout cells as detected in immunoprecipitation as well as confocal immunofluorescence microscopy studies, which indicated that NCT interacted with ERGIC-53 prior to its association with the active gamma-secretase complex.
Morais
Vanessa A
VA
Instituto de Tecnologia Química e Biológica/Instituto de Biologia Experimental e Tecnológica, Avenida da República, Apartado 127, 2781-901 Oeiras, Portugal.
Brito
Catarina
C
Pijak
Donald S
DS
Crystal
Adam S
AS
Fortna
Ryan R
RR
Li
Tong
T
Wong
Phil C
PC
Doms
Robert W
RW
Costa
Júlia
J
D053829:Amyloid Precursor Protein Secretases / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D037281:Calnexin / Q000378:metabolism*; D002478:Cells, Cultured; D006031:Glycosylation; D006801:Humans; D037102:Lectins / Q000378:metabolism*; D037241:Mannose-Binding Lectins / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009842:Oligopeptides / Q000502:physiology; D009844:Oligosaccharides; D010455:Peptides; D015800:Protozoan Proteins; D015398:Signal Transduction; D014162:Transfection
C084004:LMAN1 protein, human; D037102:Lectins; D037241:Mannose-Binding Lectins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009842:Oligopeptides; D009844:Oligosaccharides; C449186:PS1 antigen; D010455:Peptides; D015800:Protozoan Proteins; C042968:knob protein, Plasmodium falciparum; C413604:nicastrin protein; D037281:Calnexin; D053829:Amyloid Precursor Protein Secretases