SERCA (Sarco/Endoplasmic Reticulum Ca²⁺-ATPase)

SERCA (Sarco/Endoplasmic Reticulum Ca²⁺-ATPase)

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<h3 style="margin-top:0; border-bottom:1px solid #ccc;">Protein Information</h3>
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<tr><td style="padding:3px 0;"><strong>Symbols:</strong></td><td>ATP2A1-3</td></tr>
<tr><td style="padding:3px 0;"><strong>UniProt:</strong></td><td>[ATP2A1](https://www.uniprot.org/uniprot/P04177), [ATP2A2](https://www.uniprot.org/uniprot/P16615), [ATP2A3](https://www.uniprot.org/uniprot/Q93084)</td></tr>
<tr><td style="padding:3px 0;"><strong>Molecular Weight:</strong></td><td>110 kDa</td></tr>
<tr><td style="padding:3px 0;"><strong>Location:</strong></td><td>Endoplasmic/sarcoplasmic reticulum membrane</td></tr>
<tr><td style="padding:3px 0;"><strong>PDB:</strong></td><td>[1SU4](https://www.rcsb.org/structure/1SU4), [3N5K](https://www.rcsb.org/structure/3N5K)</td></tr>
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<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
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Overview

SERCA (Sarco/Endoplasmic Reticulum Ca²⁺-ATPase)

<div class="infobox" style="float:right; width:280px; background:#f8f9fa; border:1px solid #ddd; padding:10px; margin:0 0 10px 10px; font-size:0.9em;">
<h3 style="margin-top:0; border-bottom:1px solid #ccc;">Protein Information</h3>
<table style="width:100%; border-collapse:collapse;">
<tr><td style="padding:3px 0;"><strong>Symbols:</strong></td><td>ATP2A1-3</td></tr>
<tr><td style="padding:3px 0;"><strong>UniProt:</strong></td><td>[ATP2A1](https://www.uniprot.org/uniprot/P04177), [ATP2A2](https://www.uniprot.org/uniprot/P16615), [ATP2A3](https://www.uniprot.org/uniprot/Q93084)</td></tr>
<tr><td style="padding:3px 0;"><strong>Molecular Weight:</strong></td><td>110 kDa</td></tr>
<tr><td style="padding:3px 0;"><strong>Location:</strong></td><td>Endoplasmic/sarcoplasmic reticulum membrane</td></tr>
<tr><td style="padding:3px 0;"><strong>PDB:</strong></td><td>[1SU4](https://www.rcsb.org/structure/1SU4), [3N5K](https://www.rcsb.org/structure/3N5K)</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Overview

SERCA (Sarco/Endoplasmic Reticulum Ca²⁺-ATPase) pumps calcium ions from the cytosol into the endoplasmic reticulum (ER), maintaining the steep calcium gradient essential for calcium signaling. Three isoforms (SERCA1-3, encoded by ATP2A1-3) serve different tissues, with SERCA2b and SERCA3 prominent in [neurons](/entities/neurons). SERCA dysfunction contributes to calcium dysregulation in Alzheimer's disease, Parkinson's disease, and Huntington's disease.[@maclennan1997][@strehler2004]

Structure and Isoforms

Domain Architecture

SERCA is a P-type ATPase with key functional domains:[@toyoshima2000]

• A (actuator) domain: Contains phosphorylated aspartate residue
• N (nucleotide-binding) domain: Binds ATP
• P (phosphorylation) domain: Receives phosphate from ATP
• Transmembrane domain: 10 helices forming calcium transport pathway
• Calcium binding sites: Two high-affinity sites (sites I and II)

Isoforms

Three genes encode SERCA isoforms with distinct properties:

| Isoform | Gene | Tissue | Notes |
|---------|------|--------|-------|
| SERCA1a/1b | ATP2A1 | Fast-twitch skeletal muscle | Developmental switch |
| SERCA2a/2b | ATP2A2 | Cardiac muscle, neurons | 2b is housekeeping isoform |
| SERCA3 | ATP2A3 | Epithelial, hematopoietic, neurons | Lower calcium affinity |

SERCA2b is the predominant neuronal isoform.[@wuytack2003]

Normal Function

Calcium Sequestration

SERCA maintains ER calcium homeostasis:

ER Calcium Store Maintenance

SERCA activity creates:[@brini2014]

• High ER calcium: 100-800 μM in ER lumen vs. ~100 nM cytosol
• Calcium signaling capacity: Stores for IP₃R and RyR release
• Protein folding environment: Chaperones require calcium
• ER stress prevention: Maintains [UPR](/entities/unfolded-protein-response) homeostasis

Regulation

SERCA activity is modulated by:

• Phospholamban: Cardiac inhibitor, phosphorylation relieves inhibition
• Sarcolipin: Muscle-specific regulator
• ER calcium concentration: Product inhibition
• Oxidation: Cysteine modification affects activity

Role in Neurodegeneration

Alzheimer's Disease

SERCA dysfunction in AD:[@green2008]

• [Aβ](/proteins/amyloid-beta) oligomers impair SERCA activity
• Presenilin mutations affect ER calcium handling
• Reduced ER calcium stores in AD neurons
• Enhanced susceptibility to excitotoxicity
• SERCA inhibition increases Aβ production ([γ-secretase](/entities/gamma-secretase) effect)

Parkinson's Disease

ER-mitochondria calcium crosstalk disrupted in PD:[@selvaraj2012]

• [α-synuclein](/proteins/alpha-synuclein) oligomers inhibit SERCA
• Parkin mutations impair SERCA quality control
• Reduced ER calcium alters mitochondrial calcium uptake
• Contributes to dopaminergic vulnerability

Huntington's Disease

Mutant [huntingtin](/proteins/huntingtin) impacts SERCA:[@higo2010]

• mHTT impairs ER calcium handling
• Reduced SERCA2b expression in HD models
• ER calcium store depletion
• Altered calcium-dependent transcription

Bipolar Disorder

An unexpected connection:[@mynettjohnson2000]

• SERCA2 (ATP2A2) variants associated with bipolar disorder
• Mood stabilizers may affect SERCA activity
• Calcium dysregulation in neuronal excitability

Therapeutic Targeting

SERCA Activators

Strategies to enhance SERCA function:

• CDN1163: Small molecule allosteric activator
• Gene therapy: AAV-SERCA delivery
• Thyroid hormone: Upregulates SERCA expression
• Exercise: Increases SERCA2a expression

SERCA Inhibitors (Research Tools)

Used to study calcium dynamics:

• Thapsigargin: Potent irreversible inhibitor
• Cyclopiazonic acid (CPA): Reversible inhibitor
• BHQ (2,5-di-tert-butyl-1,4-benzohydroquinone): Reversible inhibitor

Clinical Applications

• Heart failure (SERCA2a gene therapy - CUPID trials)
• Potential for neurodegenerative disease
• Challenges: [Blood-brain barrier](/entities/blood-brain-barrier), isoform selectivity

See Also

• IP3 Receptor
• [Ryanodine Receptor](/entities/ryanodine-receptor)
• Calcium Dysregulation in Neurodegeneration
• [ER Stress](/mechanisms/er-stress)
• Store-Operated Calcium Entry