NAPSA (Napsin A Aspartic Peptidase)
A key aspartic protease involved in pulmonary surfactant processing and lung function.
Gene Information Card
| Symbol | NAPSA |
|---|---|
| Full Name | Napsin A Aspartic Peptidase |
| Gene Type | protein-coding |
| Chromosomal Location | 19q13.33 |
| NCBI Gene ID | 9476 ncbi.nlm.nih.gov/gene/9476 |
| Ensembl ID | ENSG00000131470 |
| UniProt ID | O96009 |
| OMIM ID | 604647 |
| HGNC ID | HGNC:13392 |
| Aliases | KAP, NAP1, NAPA, SNAPA |
Description
The NAPSA gene encodes napsin A, an aspartic protease that is predominantly expressed in the lung and kidney. In the lung, napsin A is involved in the proteolytic processing of surfactant protein B (SP-B), which is essential for reducing surface tension and maintaining alveolar stability. Napsin A is also used as an immunohistochemical marker for lung adenocarcinoma and is implicated in various pulmonary and renal disorders.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Lung adenocarcinoma | NAPSA expression is frequently upregulated in lung adenocarcinoma; used as a diagnostic biomarker. | ClinVar, COSMIC |
| Surfactant metabolism dysfunction | Deficiency in napsin A may impair SP-B processing, leading to respiratory distress. | OMIM #604647 |
| Renal cell carcinoma | NAPSA expression is detected in a subset of renal cell carcinomas, particularly papillary type. | NCBI Gene, COSMIC |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Lung | 112.5 | High |
| Kidney | 45.2 | Medium |
| Spleen | 1.3 | Low |
| Liver | 0.8 | Low |
| Brain | 0.2 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| A549 (lung adenocarcinoma) | 85.6 | High expression; used as positive control |
| NCI-H1975 (lung adenocarcinoma) | 72.3 | Moderate expression |
| HEK293 (embryonic kidney) | 12.1 | Low expression |
| MCF7 (breast cancer) | 0.5 | Not detected |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.44C>T (p.Pro15Leu) | Missense | Rare | Unknown functional effect |
| c.346G>A (p.Gly116Arg) | Missense | Rare | Potential loss of function |
| c.502C>T (p.Arg168Trp) | Missense | Rare | Reported in lung adenocarcinoma |
Mutation functional classification
Loss of Function (LOF)
Rare missense variants (e.g., p.Gly116Arg) may reduce enzymatic activity, potentially impairing surfactant processing.
Gain of Function (GOF)
No confirmed gain-of-function mutations reported.
Dominant Negative (DN)
No evidence of dominant-negative effects.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Lung surfactant metabolism (Reactome: R-HSA-5683826)
• Aspartic protease family (UniProt)
Protein Summary
Napsin A is a 420-amino acid aspartic protease synthesized as a preproprotein that undergoes proteolytic cleavage to generate the active enzyme. It is localized to lysosomes and lamellar bodies in type II pneumocytes, where it processes surfactant protein B. The protein contains two conserved aspartic acid residues (Asp32 and Asp215) essential for catalytic activity. Napsin A is a well-established immunohistochemical marker for primary lung adenocarcinoma and is also expressed in normal kidney proximal tubules.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| NAPSA Knockout HEK293 Cell Line | EDJ-KQ6600 | Human | 9476 | Details Get a Quote |
| NAPSA Knockout A-549 Cell Line | EDC90649 | Human | 9476 | Details Get a Quote |
| NAPSA Knockout HCT 116 Cell Line | EDJ-KQ30825 | Human | 9476 | Details Get a Quote |
| NAPSA Knockout HeLa Cell Line | EDJ-KQ55176 | Human | 9476 | Details Get a Quote |
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