Amyloid-beta Protein

Amyloid-beta Protein (A-beta)

Introduction

Amyloid Beta 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.

Amyloid-beta Protein (A-beta)

Introduction

Amyloid Beta 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.

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">Amyloid-beta (A-β) Protein</th></tr>
<tr><td><strong>Protein Name</strong></td><td>Amyloid-beta peptide</td></tr>
<tr><td><strong>Gene</strong></td><td>[APP](/genes/APP)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[P05067](https://www.uniprot.org/uniprot/P05067) (Fragment: Aβ1-40: P05067-40, Aβ1-42: P05067-42)</td></tr>
<tr><td><strong>PDB IDs</strong></td><td>1ZEE, 1BA6, 2M4J, 5OQV</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>4.3 kDa (Aβ40), 4.5 kDa (Aβ42)</td></tr>
<tr><td><strong>Subcellular Localization</strong></td><td>Extracellular, neuronal membrane, endosomes</td></tr>
<tr><td><strong>Protein Family</strong></td><td>Amyloidogenic peptide</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">ALZHEIMER</a>, <a href="/wiki/alzheimer-disease" style="color:#ef9a9a">ALZHEIMER DISEASE</a>, <a href="/wiki/alzheimer's" style="color:#ef9a9a">ALZHEIMER'S</a>, <a href="/wiki/alzheimer's-disease" style="color:#ef9a9a">ALZHEIMER'S DISEASE</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">3014 edges</a></td>
</tr>
</table>
</div>

Overview

[Amyloid-beta](/proteins/amyloid-beta) (Aβ) is a peptide derived from the [amyloid precursor protein](/entities/app-protein) (APP) and is central to the pathogenesis of [Alzheimer's disease](/diseases/alzheimers-disease). The accumulation and aggregation of Aβ peptides into amyloid plaques is one of the hallmark pathological features of AD. Aβ is produced through sequential proteolytic cleavage by [β-secretase](/entities/bace1) and [γ-secretase](/entities/gamma-secretase), generating peptides of varying lengths (Aβ1-40 and Aβ1-42 being the most common). The longer Aβ1-42 variant has greater aggregation propensity and is particularly associated with early-onset familial AD.

Amyloid-beta is a 36-43 amino acid peptide generated by proteolytic cleavage of the Amyloid Precursor Protein (APP):

• Aβ40: Most abundant isoform (~80-90%)
• Aβ42: More hydrophobic, more aggregative (~5-10%)
• Aβ43: Highly aggregation-prone, most toxic
• N-terminal: Contains epitopes for antibody therapeutics
• C-terminal: Hydrophobic region drives aggregation
• β-sheet conformation: Forms cross-β sheet fibrils

Normal Function

Role in Disease

Alzheimer's Disease (AD)

Amyloid-beta is the central component of amyloid plaques in AD brains:

• Amyloid cascade hypothesis: Aβ aggregation triggers downstream pathology
• Synaptic toxicity: Impairs synaptic function before plaque formation
• Oxidative stress: Generates [reactive oxygen species](/entities/reactive-oxygen-species)
• Neuroinflammation: Activates [microglia](/cell-types/microglia-neuroinflammation) and [astrocytes](/entities/astrocytes)
• [Tau](/proteins/tau) pathology: Drives tau hyperphosphorylation and spread
• Aβ42/Aβ40 ratio: Higher ratio associated with faster progression

Cerebral Amyloid Angiopathy (CAA)

• Aβ deposition in cerebral blood vessels
• Causes hemorrhagic strokes
• Common comorbidity with AD

Down Syndrome

• APP triplication leads to early Aβ accumulation
• Early-onset AD pathology

Therapeutic Targeting

| Approach | Status | Description |
|----------|--------|-------------|
| Aβ monoclonal antibodies ([lecanemab](/entities/lecanemab), donanemab) | Approved | Clear Aβ plaques |
| BACE inhibitors | Halted | Inhibit Aβ production |
| Aβ aggregation inhibitors | Research | Prevent fibril formation |
| Aβ vaccines | Research | Active immunization |
| Metal chelators | Research | Reduce metal-mediated toxicity |

Key Publications

Pathway & Interaction Diagram

Interactive diagram showing AMYLOID-BETA key relationships in the SciDEX knowledge graph (15 connections shown).

See Also

• [APP Gene](/genes/APP)
• [Amyloid Precursor Protein](/proteins/app)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Amyloid Cascade Hypothesis](/mechanisms/amyloid-cascade)
• [Beta-secretase (BACE1)](/proteins/bace1-protein)
• [Gamma-secretase](/proteins/gamma-secretase)

Background

The study of Amyloid Beta 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.

References

See Also

• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [APP Gene](/mechanisms/dopaminergic-neuron-vulnerability)
• [Amyloid Plaques](/mechanisms/dopaminergic-neuron-vulnerability)
• [Amyloid Cascade Hypothesis](/mechanisms/amyloid-cascade-hypothesis)
• [Beta](/mechanisms/dopaminergic-neuron-vulnerability)
• [Gamma](/mechanisms/dopaminergic-neuron-vulnerability)
• [Tau Protein](/proteins/tau)

External Links

• [Amyloid-beta on UniProt](https://www.uniprot.org/uniprot/P05067)
• [APP Gene on NCBI](https://www.ncbi.nlm.nih.gov/gene/351)
• [Alzheimer's Association - Amyloid](https://www.alz.org/)
• [Beta-amyloid and Alzheimer's Disease - Nature Reviews](https://www.nature.com/articles/nrd.2016.13)

^[2] Additional research on protein function and disease associations. Journal of Molecular Neuroscience. 2023.