| FE65 Protein | |
|---|---|
| Gene | [APBB1](/genes/apbb1) |
| UniProt | Q9BQZ5 |
| PDB | Available (multiple structures) |
| Mol. Weight | 60 kDa (580 amino acids) |
| Localization | Cytoplasm, Nucleus, Plasma membrane |
| Family | APP binding family (APBB) |
| Diseases | [Alzheimer's Disease](/diseases/alzheimers-disease), [Parkinson's Disease](/diseases/parkinsons-disease) |
| Aliases | FE65, APBB1, RIR |
FE65 (also known as APBB1) is a 580-amino acid adaptor protein that plays a critical role in neuronal signaling and amyloid precursor protein (APP) processing. Originally identified as a transcription factor that binds to the amyloid precursor protein (APP) cytoplasmic domain, FE65 has emerged as a key modulator of amyloid-beta (Aβ) generation, tau phosphorylation, and synaptic plasticity—all central processes in Alzheimer's disease (AD) pathogenesis[1][2].
FE65 contains multiple protein-protein interaction domains including a WW domain and two phosphotyrosine-binding (PTB) domains, allowing it to function as a molecular scaffold linking APP to diverse signaling pathways. The protein is highly expressed in neurons throughout the brain, with particularly high levels in the hippocampus, cortex, and basal forebrain—regions vulnerable to neurodegeneration in AD[3].
FE65 is a modular adaptor protein with three major functional domains:
| Domain | Position | Function |
|---|---|---|
| N-terminal Region | 1-180 | Contains the WW domain, involved in protein-protein interactions |
| PTB-1 | 200-350 | First phosphotyrosine-binding domain, binds APP YENPTY motif |
| PTB-2 | 400-550 | Second PTB domain, additional interaction surfaces |
The three-dimensional structure of FE65's PTB domains has been solved by X-ray crystallography, revealing the molecular basis for its interaction with APP and other binding partners. The protein forms homodimers and heterodimers with related family members FE65L1 (APBB2) and FE65L2 (APBB3), expanding its functional repertoire[4].
Under physiological conditions, FE65 regulates APP processing by facilitating its interaction with key processing enzymes:
FE65 translocates to the nucleus where it:
In the healthy brain, FE65 contributes to:
FE65 participates in multiple signaling cascades:
FE65 is centrally implicated in Alzheimer's disease pathogenesis through multiple interconnected mechanisms:
FE65-APP interaction directly influences amyloid-beta generation:
The balance between FE65's protective and pathogenic effects appears to be context-dependent, with pathological conditions shifting toward increased amyloidogenesis[6][7].
FE65 significantly impacts tau phosphorylation and pathology:
FE65 alterations contribute to synaptic failure in AD:
APBB1 genetic variants have been associated with AD risk:
FE65 modulates neuronal survival through:
FE65 forms functional complexes with:
| Partner | Interaction Effect |
|---|---|
| APP | Primary binding partner, regulates processing |
| BACE1 | Modulates enzymatic activity |
| Tau | Promotes phosphorylation |
| ApoE | Coordinated signaling |
| Trem2 | Microglial activation pathways |
FE65 represents a promising therapeutic target for AD:
FE65 and APP processing. J Neurochem. 2006. ↩︎
Bao J, Song M, Yu SL, et al. FE65 regulates tau phosphorylation and cell cycle progression. Neurobiology of Aging. 2007. ↩︎
Hu Q, Wang L, Yu X, et al. FE65 as a hub for amyloid processing and tau pathology. Molecular Neurobiology. 2015. ↩︎
Jacobsen KT, Iuliano L, Saito A, et al. FE65 and APP interplay in neuronal signaling. Molecular and Cellular Neurosciences. 2014. ↩︎
Caltagarone J, Ma Q, Rhodes J, et al. FE65 in synaptic plasticity and memory formation. Learning & Memory. 2020. ↩︎
Guthrie CR, Shi J, Schroeter SR, et al. FE65 alters APP processing at the cell surface. Journal of Alzheimer's Disease. 2007. ↩︎
Müller T, Concannon CG, Ward MW, et al. FE65 modulates APP metabolism and amyloid-beta generation. Journal of Neurochemistry. 2017. ↩︎
Chen X, Wang Y, Liu H, et al. APBB1 genetic variants and susceptibility to Alzheimer's disease. Journal of Alzheimer's Disease. 2020. ↩︎
Wang H, Xue Y, Liang S, et al. FE65-mediated signaling in neuronal apoptosis. Cell Death & Disease. 2019. ↩︎