| First Author | Zhang X | Year | 2012 |
| Journal | Proc Natl Acad Sci U S A | Volume | 109 |
| Issue | 22 | Pages | 8534-9 |
| PubMed ID | 22586122 | Mgi Jnum | J:184754 |
| Mgi Id | MGI:5426285 | Doi | 10.1073/pnas.1202691109 |
| Citation | Zhang X, et al. (2012) Identification of a tetratricopeptide repeat-like domain in the nicastrin subunit of gamma-secretase using synthetic antibodies. Proc Natl Acad Sci U S A 109(22):8534-9 |
| abstractText | The gamma-secretase complex, composed of presenilin, anterior-pharynx-defective 1, nicastrin, and presenilin enhancer 2, catalyzes the intramembranous processing of a wide variety of type I membrane proteins, including amyloid precursor protein (APP) and Notch. Earlier studies have revealed that nicastrin, a type I membrane-anchored glycoprotein, plays a role in gamma-secretase assembly and trafficking and has been proposed to bind substrates. To gain more insights regarding nicastrin structure and function, we generated a conformation-specific synthetic antibody and used it as a molecular probe to map functional domains within nicastrin ectodomain. The antibody bound to a conformational epitope within a nicastrin segment encompassing residues 245-630 and inhibited the processing of APP and Notch substrates in in vitro gamma-secretase activity assays, suggesting that a functional domain pertinent to gamma-secretase activity resides within this region. Epitope mapping and database searches revealed the presence of a structured segment, located downstream of the previously identified DAP domain (DYIGS and peptidase; residues 261-502), that is homologous to a tetratricopeptide repeat (TPR) domain commonly involved in peptide recognition. Mutagenesis analyses within the predicted TPR-like domain showed that disruption of the signature helical structure resulted in the loss of gamma-secretase activity but not the assembly of the gamma-secretase and that Leu571 within the TPR-like domain plays an important role in mediating substrate binding. Taken together, these studies offer provocative insights pertaining to the structural basis for nicastrin function as a "substrate receptor" within the gamma-secretase complex. |
