Proteins Overview is a protein. This page describes its structure, normal nervous system function, role in neurodegenerative disease, and potential as a therapeutic target.
This section covers proteins relevant to neurodegenerative diseases, including disease-associated proteins, therapeutic targets, and biomarkers. Understanding protein function, aggregation mechanisms, and therapeutic targeting is fundamental to developing disease-modifying treatments.
¶ Amyloid and APP Family
- Tau (MAPT) — microtubule-associated protein that forms neurofibrillary tangles. Six tau isoforms exist in human brain.
- Phosphorylated tau — tau species with altered function in disease. Over 80 potential phosphorylation sites.
- Alpha-synuclein — Lewy body component in Parkinson's disease. 140 amino acid protein with N-terminal lipid-binding domain.
- Beta-synuclein — synuclein family member with protective properties against aggregation.
- Gamma-synuclein — expressed in peripheral nervous system, implicated in breast cancer.
- TDP-43 — RNA-binding protein aggregating in ALS/FTD. Loss of nuclear function contributes to disease.
- FUS — TLS protein in ALS/FTD. Similar pathology to TDP-43.
- TARDBP — gene encoding TDP-43. Over 50 mutations cause familial ALS.
- SOD1 — superoxide dismutase 1, mutated in familial ALS. First ALS gene discovered.
- Huntingtin — mutant protein in Huntington's disease. Polyglutamine expansion causes toxicity.
- TREM2 — triggering receptor on myeloid cells 2. AD risk variant (R47H) impairs microglia function.
- CD33 — sialic acid-binding immunoglobulin-like lectin. Risk variant increases expression.
- APOE — apolipoprotein E, major AD risk gene. APOE4 increases amyloid deposition.
- Synuclein — presynaptic protein in Lewy bodies. Normal function in synaptic vesicle regulation.
- PSD-95 — postsynaptic density protein. Scaffold for excitatory synapses.
- NMDA receptors — ionotropic glutamate receptors. Critical for synaptic plasticity.
- AMPA receptors — ionotropic glutamate receptors. GluA2 subunit regulates calcium permeability.
¶ Kinases and Phosphatases
- GSK3β — glycogen synthase kinase 3 beta. Hyperactive in AD, phosphorylates tau.
- CDK5 — cyclin-dependent kinase 5. Activator p25 drives pathological phosphorylation.
- PP2A — protein phosphatase 2A. Major tau phosphatase, activity reduced in AD.
| Category |
Key Proteins |
Disease Relevance |
| Aggregation |
APP, Tau, α-syn, TDP-43 |
Core pathology |
| Synaptic |
Synaptophysin, PSD-95, NMDA-R |
Cognitive decline |
| Inflammatory |
TREM2, CD33, IL-1β |
Neuroinflammation |
| Transport |
Dynein, Kinesin |
Axonal transport |
| Transcription |
TDP-43, FUS |
RNA metabolism |
| Chaperones |
Hsp70, Hsp90 |
Protein folding |
Many proteins serve as biomarkers for diagnosis and progression:
- NfL (Neurofilament Light Chain) — marker of axonal damage. Elevates in ALS, PD, AD.
- p-tau — tau phosphorylation state. Specific for AD vs other dementias.
- Neurogranin — synaptic dysfunction marker. Elevated in AD.
- YKL-40 — astrocyte activation. Non-specific inflammation marker.
Key protein targets for therapeutic development:
- Amyloid-beta — monoclonal antibodies (lecanemab, donanemab), vaccines
- Tau — monoclonal antibodies, kinase inhibitors (failed), aggregation inhibitors
- Alpha-synuclein — aggregation inhibitors, immunotherapy, ASO therapies
- BACE1 — beta-secretase inhibitor (failed due to side effects)
- Gamma-secretase — modulators (failed), not inhibitors
¶ Protein Structure and Aggregation
Protein misfolding and aggregation follows a nucleation-dependent process:
- Native protein misfolds
- Oligomer formation (toxic species)
- Protofibril development
- Fibril maturation (visible plaques/tangles)
- Immunotherapy: Active vaccines or passive antibodies
- Small molecule inhibitors: Prevent aggregation or promote clearance
- Gene silencing: ASO or RNAi to reduce expression
- Enhance clearance: Promote autophagy or unfolded protein response
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