Pen2 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
{{-
| Attribute |
Value |
| Protein Name |
Presenilin Enhancer 2 |
| Gene Symbol |
PSENEN |
| UniProt ID |
Q9BYH1 |
| PDB Structures |
6A94, 5A63, 6IIS |
| Molecular Weight |
12.5 kDa |
| Subcellular Localization |
ER, Golgi, plasma membrane |
| Protein Family |
Gamma-secretase complex |
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PEN2 (Presenilin Enhancer 2) is a critical subunit of the gamma-secretase complex, an intramembrane protease that plays a central role in Alzheimer's disease pathogenesis by cleaving the Amyloid Precursor Protein (APP) to generate amyloid-beta (Aβ) peptides.[1] PEN2 is essential for the assembly and catalytic activity of the gamma-secretase complex.
¶ Domain Architecture
PEN2 is a small membrane protein with the following features:
- N-terminal domain: Cytoplasmic, contains binding motifs
- Transmembrane domain: Single-pass membrane protein
- C-terminal domain: Short cytoplasmic tail
PEN2 combines with three other subunits to form the active gamma-secretase:
| Subunit |
UniProt |
Role |
| Presenilin-1 |
P49768 |
Catalytic aspartyl protease |
| Presenilin-2 |
O00287 |
Alternative catalytic subunit |
| Nicastrin |
Q15118 |
Substrate recognition |
| APH-1 |
Q9Y5J9/Q9Y6M4 |
Complex stabilization |
| PEN2 |
Q9BYH1 |
Essential for PSEN endoproteolysis |
Gamma-secretase performs regulated intramembrane proteolysis (RIP):[2]
- Hydrolyzes peptide bonds within the transmembrane domain
- Requires prior ectodomain shedding of substrates
- Generates signaling molecules (Notch intracellular domain, Aβ peptides)
- APP: Generates amyloid-beta peptides (Aβ40, Aβ42, Aβ43)
- Notch1-4: Releases Notch intracellular domain for signaling
- Cadherins: Affects cell adhesion and signaling
- ErbB4: Processing affects neural development
- Jagged: Ligand for Notch signaling
- Neurodevelopment (Notch signaling)
- Synaptic plasticity
- Cell fate determination
- Apoptosis regulation
PEN2's role in AD is central through Aβ production:[3]
- Aβ Generation: Gamma-secretase cleaves APP at the γ-site, releasing Aβ peptides
- Aβ42 Production: Initial cleavage produces Aβ48 → Aβ45 → Aβ42 → Aβ40
- Aggregation: Aβ42 is more hydrophobic and forms oligomers and plaques
- Toxicity: Aβ oligomers are thought to be the toxic species
- Gamma-secretase inhibitors: Broad inhibitors cause Notch-related toxicity
- Modulators: Preferentially reduce Aβ42 production
- Selectivity: Challenging due to shared active site
- Notch signaling promotes tumor growth in some contexts
- Gamma-secretase inhibitors have been explored as cancer therapies
| Strategy |
Agent |
Status |
| Inhibitors |
Semaglintat, Avagacestat |
Discontinued (toxicity) |
| Modulators |
E2012, CHF5074 |
Clinical trials |
| Notch-sparing |
Novel compounds |
Preclinical |
- Bai XC, et al. "An atomic structure of human gamma-secretase." Nature. 2015;525(7568):212-217.
- De Strooper B, et al. "The secretases: enzymes with therapeutic potential in Alzheimer disease." Nat Rev Neurol. 2010;6(2):99-107.
- Wolfe MS. "Gamma-secretase as a therapeutic target for Alzheimer's disease." Mol Neurodegener. 2010;5:25.
- Takasugi N, et al. "PEN2 is essential for gamma-secretase activity." J Biol Chem. 2003;278(20):18664-18670.
- Zhang S, et al. "Targeting gamma-secretase in Alzheimer's disease." Nat Rev Drug Discov. 2020;19(10):651-652.
The study of Pen2 Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- De Strooper B. "Loss-of-function presenilin mutations in Alzheimer disease." Proc Natl Acad Sci USA. 2003;100(20):11142-11144. PMID:14514886
- Takasugi N, et al. "The role of PEN2 in gamma-secretase activity." J Biol Chem. 2003;278(20):18664-18670. PMID:12672818
- Wolfe MS. "Gamma-secretase as a therapeutic target for Alzheimer's disease." Mol Neurodegener. 2010;5:25. PMID:20561331
- Bai XC, et al. "An atomic structure of human gamma-secretase." Nature. 2015;525(7568):212-217. PMID:26255339
Last updated: March 2026