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Updated: Apr 12, 2026

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
Akt1 phosphorylates Nicastrin to regulate its protein stability and activity
Eun-Hye Jo1, Ji-Seon Ahn1, Jung-Soon Mo1
1Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Korea.
Akt1 kinase activity degrades Nicastrin (NCT), a key gamma-secretase component. This phosphorylation-dependent process inhibits gamma-secretase activity, impacting amyloid precursor protein processing.
Area of Science:
- Molecular and Cellular Biology
- Neuroscience
- Biochemistry
Background:
- Gamma-secretase is a multiprotein complex crucial for cleaving type-I membrane proteins like Notch and amyloid precursor protein (APP).
- Nicastrin (NCT) is an essential subunit of the gamma-secretase complex, acting as a substrate receptor.
Purpose of the Study:
- To investigate the role of Akt1 in regulating gamma-secretase activity.
- To elucidate the mechanism by which Akt1 affects Nicastrin (NCT) stability and function.
Main Methods:
- Investigated Akt1's effect on NCT protein stability and degradation pathways (proteasomal and lysosomal).
- Utilized cell-based assays to examine Akt1-NCT interaction and NCT phosphorylation at Ser437.
- Assessed the impact of Akt1 on gamma-secretase activity.
Main Results:
- Akt1 directly interacts with NCT and promotes its degradation via proteasomal and lysosomal pathways.
- Akt1 phosphorylates NCT at Ser437, significantly reducing NCT protein stability.
- Inhibition of Akt1 kinase activity prevented NCT degradation, leading to increased NCT levels and gamma-secretase activity.
Conclusions:
- Akt1 acts as a negative regulator of gamma-secretase activity.
- Akt1 phosphorylates and degrades NCT, thereby modulating gamma-secretase function.
- This mechanism offers a potential target for therapeutic interventions related to APP processing.
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