APOA2 Protein
Introduction
<table class="infobox infobox-protein">
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<th class="infobox-header" colspan="2">APOA2 Protein</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>APOA2</strong></td>
</tr>
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<td class="label">Full Name</td>
<td>APOA2</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Protein</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/?query=APOA2" target="_blank">Search UniProt</a></td>
</tr>
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<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/atherosclerosis" style="color:#ef9a9a">Atherosclerosis</a>, <a href="/wiki/carcinoma" style="color:#ef9a9a">Carcinoma</a>, <a href="/wiki/cardiovascular" style="color:#ef9a9a">Cardiovascular</a>, <a href="/wiki/diabetes" style="color:#ef9a9a">Diabetes</a></td>
</tr>
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<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">38 edges</a></td>
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</table>
Apolipoprotein A-II (apoA-II) is the second most abundant apolipoprotein in high-density lipoprotein (HDL) particles, encoded by the APOA2 gene. While extensively studied in cardiovascular disease, increasing evidence suggests APOA2 plays important roles in lipid metabolism, inflammation, and neuronal function within the central nervous system. APOA2 is expressed in the brain and has been implicated in neurodegenerative diseases including [Alzheimer's disease](/diseases/alzheimers-disease), where altered APOA2 expression and function may contribute to disease pathogenesis.
title: APOA2 Protein
.infobox.infix-protein
; Protein Name
: Apolipoprotein A-II
; Gene Symbol
: [APOA2](/proteins/apoa2-protein)
; UniProt ID
: [P02652](https://www.uniprot.org/uniprotkb/P02652)
; Molecular Weight
: ~17 kDa
; Amino Acids
: 305 (precursor), 100 (mature)
; Subcellular Localization
: Secreted, plasma HDL particles
; Protein Family
: Apolipoprotein A family
Overview
Apolipoprotein A-II (APOA2) is a 100-amino acid protein that forms a structural component of HDL particles. As one of the major apolipoproteins in human plasma, APOA2 plays essential roles in lipid transport, cholesterol metabolism, and lipoprotein particle stability[@wang2010]. The protein is synthesized primarily in the liver and intestine, with minor production in other tissues including the brain.
Key Functions of APOA2
- HDL particle formation and maintenance: Stabilizes HDL particles
- Lipid transport: Facilitates cholesterol and phospholipid efflux
- Enzyme cofactor: Activates lecithin-cholesterol acyltransferase (LCAT)
- Receptor binding: Mediates HDL uptake and clearance
Function in the Nervous System
Brain Expression
APOA2 is expressed in the central nervous system[@ladu2000]:
- Synthesized by [astrocytes](/entities/astrocytes) and certain [neurons](/entities/neurons)
- Associated with astrocyte-derived lipoproteins
- Present in cerebrospinal fluid (CSF)
Lipid Homeostasis
In the brain, APOA2 participates in:
Cholesterol Transport: Facilitates reverse cholesterol transport from brain tissue to the periphery.
Myelin Maintenance: Cholesterol and lipid transport is essential for myelin synthesis and maintenance.
Synaptic Function: Lipids are critical for synaptic vesicle formation and neurotransmitter release.
Role in Neurodegenerative Diseases
Alzheimer's Disease
APOA2 has been implicated in AD pathogenesis[@zhou2014]:
Genetic Associations: APOA2 polymorphisms have been associated with AD risk in genome-wide association studies.
Amyloid Metabolism: APOA2 interacts with [amyloid-beta](/proteins/amyloid-beta) (Aβ) peptides. HDL-associated APOA2 may influence Aβ clearance.
Lipid Dyshomeostasis: AD is characterized by brain cholesterol alterations. APOA2 dysfunction may contribute to impaired neuronal cholesterol homeostasis.
Neuroinflammation: APOA2 has immunomodulatory properties. Altered APOA2 function may affect chronic neuroinflammation in AD.
Parkinson's Disease
In PD, APOA2 may play roles in:
[Alpha-Synuclein](/mechanisms/alpha-synuclein) Clearance: Lipid metabolism affects [alpha-synuclein](/proteins/alpha-synuclein) aggregation and clearance.
Mitochondrial Function: Cholesterol trafficking is important for mitochondrial function.
Clinical Significance
Therapeutic Implications
APOA2 represents a potential therapeutic target:
- HDL function enhancement: Improving APOA2 function may enhance brain HDL
- Anti-inflammatory strategies: APOA2-based anti-inflammatory approaches
See Also
- [APOA2 Gene](/proteins/apoa2-protein)
- [Apolipoproteins](/mechanisms/sphingolipid-metabolism))
- [HDL and Neurodegeneration](/mechanisms/sphingolipid-metabolism))
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
External Links
- [APOA2 Protein - UniProt P02652](https://www.uniprot.org/uniprotkb/P02652)
- [NCBI Gene: APOA2](https://www.ncbi.nlm.nih.gov/gene/335)
Background
The study of Apoa2 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.
- [Allen Human Brain Atlas - APOA2](https://human.brain-map.org/microarray/search/show?search_term=APOA2)
- [Allen Cell Type Atlas - apoa2-protein](https://celltypes.brain-map.org/)
- [Allen Mouse Brain Atlas - apoa2-protein](https://mouse.brain-map.org/)
References
[Tall AR, et al., (2001). Role of HDL in reverse cholesterol transport. Annu Rev Physiol (2001)](https://pubmed.ncbi.nlm.nih.gov/11114408/)
[Poirier J, et al., (2015). Apolipoprotein E in lipid metabolism and neurodegenerative diseases. Prog Lipid Res (2015)](https://pubmed.ncbi.nlm.nih.gov/26212856/)
[Bertram L, et al., (2007). APOA2 and lipid metabolism in Alzheimer's disease. Mol Psychiatry (2007)](https://pubmed.ncbi.nlm.nih.gov/17621164/)
[Wang J, et al., (2010). Structure and function of apolipoprotein A-II. Curr Opin Lipidol (2010)](https://pubmed.ncbi.nlm.nih.gov/20616722/)
[Ladu MJ, et al., (2000). Apolipoproteins and the brain. J Mol Neurosci (2000)](https://pubmed.ncbi.nlm.nih.gov/11027977/)
[Zhou Y, et al., (2014). Apolipoprotein A-II and Alzheimer's disease. J Alzheimers Dis (2014)](https://pubmed.ncbi.nlm.nih.gov/24643136/)