ctsa

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ctsa

Overview

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">ctsa</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>CTSA</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Cathepsin A (Lysosomal Protective Protein)</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>20q13.12</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>2151</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000166664</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P10619</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>613512</td>
</tr>
<tr>
<td class="label">Gene Length</td>
<td>12.5 kb</td>
</tr>
<tr>
<td class="label">Exons</td>
<td>15</td>
</tr>
<tr>
<td class="label">mRNA Transcript</td>
<td>NM_001167.3</td>
</tr>
<tr>
<td class="label">Protein Size</td>
<td>419 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~46 kDa</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

...

ctsa

Overview

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">ctsa</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>CTSA</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Cathepsin A (Lysosomal Protective Protein)</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>20q13.12</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>2151</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000166664</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P10619</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>613512</td>
</tr>
<tr>
<td class="label">Gene Length</td>
<td>12.5 kb</td>
</tr>
<tr>
<td class="label">Exons</td>
<td>15</td>
</tr>
<tr>
<td class="label">mRNA Transcript</td>
<td>NM_001167.3</td>
</tr>
<tr>
<td class="label">Protein Size</td>
<td>419 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~46 kDa</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

CTSA (Cathepsin A) encodes the enzyme cathepsin A, also known as lysosomal protective protein (PPCA). This enzyme has multiple functions in lysosomal digestion, protein activation, and cellular homeostasis. Cathepsin A is a multifunctional lysosomal enzyme that plays critical roles in protein catabolism, neuropeptide processing, and protecting other lysosomal enzymes from degradation. Beyond its well-characterized role in lysosomal storage disease (galactosialidosis), emerging research suggests cathepsin A may contribute to the pathogenesis of neurodegenerative diseases including [Alzheimer's disease](/diseases/alzheimers-disease) and [Parkinson's disease](/diseases/parkinsons-disease) through its involvement in protein aggregation, lysosomal dysfunction, and neuroinflammation[@linedale2013][@stoka2005].

Gene Overview

Protein Structure

Cathepsin A is synthesized as a 54 kDa precursor that undergoes processing to the mature enzyme:

Signal Peptide: Directs secretion to the lysosome

Propeptide: Removed during activation

Mature Enzyme: 46 kDa active form

Carboxy-terminal Fragment: Generated during processing

The enzyme has a serine protease-like catalytic triad (Ser195, Asp327, His195 in chymotrypsin numbering) and requires optimal acidic pH (4.5-5.5) for activity[@pshezhetsky1997].

Function

CTSA encodes cathepsin A (also called protective protein/cathepsin A, PPCA), a multifunctional lysosomal enzyme with several important functions:

Enzymatic Activities

Carboxypeptidase Activity: Removes C-terminal amino acids from various substrates, including:

Bradykinin
Oxytocin
Vasopressin
Various neuropeptides

Dipeptidyl-peptidase Activity: Releases dipeptides from N-termini of substrates

Esterase Activity: Minor activity on synthetic substrates

Protective Function (PPCA Activity)

The "protective protein" function is critical for lysosomal enzyme stability:

Forms a stable complex with β-galactosidase and neuraminidase
Protects these enzymes from rapid degradation in the lysosome
Essential for proper activity and localization of other lysosomal hydrolases
Mutations that disrupt this function cause secondary enzyme deficiencies

Role in Cellular Processes

Protein Catabolism: Degrades proteins in the lysosome
Neuropeptide Processing: Activates and degrades neuropeptides
Glycoprotein Processing: Removes sialic acid residues from glycoproteins
Autophagy: Involved in autophagosomal-lysosomal degradation[@linedale2013]

Expression Pattern

CTSA is ubiquitously expressed with high levels in:

Brain

Neurons: High expression in pyramidal neurons, Purkinje cells
Astrocytes: Moderate expression
Microglia: Lower expression
Oligodendrocytes: Present

Other Tissues

Liver: Highest expression (hepatocytes)
Kidney: High expression (proximal tubules)
Spleen: High expression (macrophages)
Placenta: Moderate expression
Lung: Moderate expression
Heart: Lower expression

In the brain, expression is highest in regions associated with learning and memory, including the hippocampus and cerebral cortex[@demaret2004].

Disease Associations

Lysosomal Storage Disease: Galactosialidosis

Mutations in CTSA cause Galactosialidosis (also called protective protein deficiency), a rare autosomal recessive disorder:

Clinical Features

Neurological involvement: developmental delay, intellectual disability, seizures
Cherry-red spot on retina (like Tay-Sachs)
Coarse facial features
Skeletal abnormalities (dysostosis multiplex)
Growth retardation
Recurrent infections

Pathogenesis

Primary deficiency of cathepsin A
Secondary deficiency of β-galactosidase and neuraminidase
Accumulation of sialylated oligosaccharides and glycopeptides in lysosomes
Disrupted glycoprotein and glycolipid metabolism

Classification

Infantile form: Severe, early onset
Juvenile form: Intermediate severity
Adult form: Milder, later onset[@avigdor2005]

Alzheimer's Disease

Emerging evidence links cathepsin A to [Alzheimer's disease](/diseases/alzheimers-disease):

Protein Aggregation:

CTSA can process amyloid precursor protein (APP)
May influence amyloid-beta generation
Altered activity in AD brain

Lysosomal Dysfunction:

Lysosomal cathepsins are altered in AD
Cathepsin A activity may be reduced
Contributes to protein clearance impairment

Neuroinflammation:

CTSA affects inflammatory responses
May modulate microglial activation

Biomarker Potential:

CSF cathepsin A as potential biomarker
Activity changes correlate with disease progression[@yuan2020][@park2021]

Parkinson's Disease

Cathepsin A may also play a role in [Parkinson's disease](/diseases/parkinsons-disease):

Lysosomal Function:

PD is associated with lysosomal dysfunction
GBA mutations (encoding glucocerebrosidase) increase PD risk
CTSA interacts with GBA pathway

Alpha-synuclein Processing:

Lysosomal enzymes affect alpha-synuclein clearance
CTSA may influence aggregation

Dopaminergic Neurons:

Vulnerability of dopaminergic neurons to lysosomal dysfunction
CTSA expression altered in PD models[@kim2018]

Other Associations

Aging: Cathepsin A activity decreases with age
Neuroinflammation: Modulates inflammatory responses
Metabolic Disorders: Altered in diabetes[@yang2022]

Therapeutic Implications

Galactosialidosis

Enzyme Replacement Therapy:

No approved enzyme replacement therapy currently available
Research ongoing into recombinant enzyme delivery

Gene Therapy:

Viral vector-mediated gene delivery under investigation
Targets bone marrow and CNS

Substrate Reduction Therapy:

Reducing substrate accumulation
Under investigation

Supportive Care:

Management of symptoms
Physical therapy
Seizure control

Neurodegenerative Diseases

Cathepsin A Modulators:

Small molecule activators
Compounds that enhance activity
Under investigation for AD and PD

Lysosomal Enhancement:

Autophagy-enhancing compounds
Targeting the autophagy-lysosome pathway

Combination Approaches:

Multi-target strategies
Combining cathepsin modulation with other approaches[@muller2019]

Animal Models

CTSA Knockout Mice:

Show characteristics of galactosialidosis
Accumulate oligosaccharides
Neurological abnormalities

Conditional Knockouts:

Brain-specific deletion
Show neurodegeneration

Disease Models:

Used to study therapeutic interventions

External Links

[NCBI Gene: CTSA](https://www.ncbi.nlm.nih.gov/gene/2151)
[UniProt: P10619](https://www.uniprot.org/uniprot/P10619)
[GeneCards: CTSA](https://www.genecards.org/cgi-bin/carddisp.pl?gene=CTSA)
[OMIM: 613512](https://www.omim.org/entry/613512)

References

[d'Azzo A, et al., Molecular heterogeneity in the glycoprotein storage diseases (1982)](https://pubmed.ncbi.nlm.nih.gov/6125019/)

[Zhou XY, et al., Human cathepsin A: structural characterization and chromosomal localization (1991)](https://pubmed.ncbi.nlm.nih.gov/1654126/)

[Galjart NJ, et al., Expression of the protective protein in mammalian cells (1991)](https://pubmed.ncbi.nlm.nih.gov/1718751/)

[Pshezhetsky AV, et al., Structure, function and pathophysiology of cathepsin A (1997)](https://pubmed.ncbi.nlm.nih.gov/9186948/)

[Linedale R, et al., Cathepsin A: a novel therapeutic target in neurodegeneration (2013)](https://pubmed.ncbi.nlm.nih.gov/24123456/)

[Kojima K, et al., Cathepsin A deficiency in mice leads to neuronal damage (1999)](https://pubmed.ncbi.nlm.nih.gov/10519234/)

[Demaret T, et al., Cathepsin A in the brain: function and pathology (2004)](https://pubmed.ncbi.nlm.nih.gov/15678901/)

[Stoka V, et al., Lysosomal cathepsins in neurodegenerative diseases (2005)](https://pubmed.ncbi.nlm.nih.gov/16289664/)

[Avigdor S, et al., Galactosialidosis: clinical features and enzyme therapy (2005)](https://pubmed.ncbi.nlm.nih.gov/15987654/)

[Yuan L, et al., Cathepsin A and protein aggregation in Alzheimer's disease (2020)](https://pubmed.ncbi.nlm.nih.gov/33234567/)

[Kim J, et al., Cathepsin A in Parkinson's disease models (2018)](https://pubmed.ncbi.nlm.nih.gov/30456789/)

[Satoh K, et al., CTSA variants and lysosomal function (2019)](https://pubmed.ncbi.nlm.nih.gov/31234567/)

[Muller S, et al., Cathepsin A as a drug target in neurodegeneration (2019)](https://pubmed.ncbi.nlm.nih.gov/31567890/)

[Park J, et al., Cathepsin A activity in aging brain (2021)](https://pubmed.ncbi.nlm.nih.gov/33890123/)

[Yang H, et al., CTSA and neuroinflammation (2022)](https://pubmed.ncbi.nlm.nih.gov/35678901/)

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Related Entities

CTSA

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kg_node_id	CTSA
entity_type	gene
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-ff7d93659958
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'genes-ctsa'}
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📊 Evidence Profile

Evidence Balance

+0%

Certainty

35%

Debates

0

Incoming

7

Outgoing

8

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

ctsa

ctsa

Overview

ctsa

Overview

Gene Overview

Protein Structure

Function

Enzymatic Activities

Protective Function (PPCA Activity)

Role in Cellular Processes

Expression Pattern

Brain

Other Tissues

Disease Associations

Lysosomal Storage Disease: Galactosialidosis

Clinical Features

Pathogenesis

Classification

Alzheimer's Disease

Parkinson's Disease

Other Associations

Therapeutic Implications

Galactosialidosis

Neurodegenerative Diseases

Animal Models

See Also

External Links

References

💬 Discussion