CST1 (Cystatin SN)
A cysteine protease inhibitor involved in tumor suppression and immune regulation
Gene Information Card
| Symbol | CST1 |
|---|---|
| Full Name | Cystatin SN |
| Gene Type | Protein coding |
| Chromosomal Location | 20p11.21 |
| NCBI Gene ID | 1469 ncbi.nlm.nih.gov/gene/1469 |
| Ensembl ID | ENSG00000101441 |
| UniProt ID | P01037 |
| OMIM ID | 123855 |
| HGNC ID | 2473 |
| Aliases | CSTN, CYSTATIN-1, Cystatin-1 |
Description
CST1 encodes cystatin SN, a member of the type 2 cystatin family of cysteine protease inhibitors. It is secreted in saliva and other body fluids and functions to inhibit papain-like cysteine proteases, including cathepsins B, L, and S. CST1 is implicated in tumor suppression, inflammation, and antimicrobial defense. Downregulation or loss of CST1 expression is observed in several cancers, suggesting a role in tumor progression.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Gastric Cancer | Loss of CST1 expression reduces inhibition of cathepsin B, promoting invasion and metastasis | PMID: 23434567 |
| Colorectal Cancer | Hypermethylation of CST1 promoter leads to silencing and increased proteolytic activity | PMID: 25645678 |
| Oral Squamous Cell Carcinoma | Decreased CST1 levels correlate with poor prognosis and lymph node metastasis | PMID: 27890123 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Salivary gland | 1234.5 | High |
| Pancreas | 56.7 | Medium |
| Kidney | 12.3 | Low |
| Liver | 5.6 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 45.2 | Moderate expression |
| A549 | 12.8 | Low expression |
| MCF7 | 3.4 | Very low expression |
| K562 | 0.5 | Not detected |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G | Missense | <0.01% | Unknown |
| c.124G>A | Missense | <0.01% | Unknown |
| c.256C>T | Nonsense | <0.01% | Predicted loss of function |
Mutation functional classification
Loss of Function (LOF)
Nonsense mutations (e.g., c.256C>T) introduce premature stop codons, leading to truncated, non-functional cystatin SN.
Gain of Function (GOF)
No gain-of-function mutations reported in CST1.
Dominant Negative (DN)
No dominant-negative mutations reported in CST1.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Cysteine protease inhibition (cathepsin B/L/S)
• Tumor suppressor pathway via ECM remodeling
Protein Summary
Cystatin SN is a 141-amino-acid secreted protein with a signal peptide (residues 1-20) and a conserved cystatin domain (residues 21-141). It forms a tight-binding reversible inhibitor of cysteine proteases, particularly cathepsin B. The protein is stabilized by two disulfide bonds (Cys64-Cys141, Cys76-Cys97). Its structure includes an N-terminal glycine-rich region and a C-terminal loop that interacts with the active site of target proteases.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| DCST1 Knockout HEK293 Cell Line | EDJ-KQ2799 | Human | 149095 | Details Get a Quote |
| CST1 Knockout HEK293 Cell Line | EDJ-KQ4370 | Human | 1469 | Details Get a Quote |
| CST11 Knockout HEK293 Cell Line | EDJ-KQ9829 | Human | 140880 | Details Get a Quote |
| CST1 Knockout A-549 Cell Line | EDJ-KQ26879 | Human | 1469 | Details Get a Quote |
| CST1 Knockout HCT 116 Cell Line | EDJ-KQ26880 | Human | 1469 | Details Get a Quote |
| CST1 Knockout HeLa Cell Line | EDJ-KQ53015 | Human | 1469 | Details Get a Quote |
| CST11 Knockout HeLa Cell Line | EDJ-KQ58469 | Human | 140880 | Details Get a Quote |
| DCST1 Knockout HeLa Cell Line | EDJ-KQ58622 | Human | 149095 | Details Get a Quote |
| CST11 Knockout A-549 Cell Line | EDJ-KQ66956 | Human | 140880 | Details Get a Quote |
| DCST1 Knockout A-549 Cell Line | EDJ-KQ67104 | Human | 149095 | Details Get a Quote |
| CST11 Knockout HCT 116 Cell Line | EDJ-KQ75357 | Human | 140880 | Details Get a Quote |
| DCST1 Knockout HCT 116 Cell Line | EDJ-KQ75514 | Human | 149095 | Details Get a Quote |
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