CST2 (Cystatin SA)
Cystatin SA gene, member of the cystatin superfamily, encoding a cysteine protease inhibitor.
Gene Information Card
| Symbol | CST2 |
|---|---|
| Full Name | Cystatin SA |
| Gene Type | protein-coding |
| Chromosomal Location | 20p11.21 |
| NCBI Gene ID | 1473 ncbi.nlm.nih.gov/gene/1473 |
| Ensembl ID | ENSG00000101230 |
| UniProt ID | P09228 |
| OMIM ID | 123857 |
| HGNC ID | 2475 |
| Aliases | CST5, cystatin SA, cystatin-2 |
Description
CST2 encodes cystatin SA, a member of the type 2 cystatin superfamily. This protein is a secreted cysteine protease inhibitor found in saliva and other body fluids. It functions to regulate proteolytic activity, particularly of cathepsins, and plays a role in antimicrobial defense and inflammation. The gene is located on chromosome 20p11.21 and is part of a cystatin gene cluster.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Periodontal disease | Reduced CST2 expression may impair inhibition of host and bacterial proteases, contributing to tissue destruction. | PMID: 20675570 |
| Sjögren's syndrome | Altered cystatin SA levels in saliva correlate with glandular dysfunction and inflammation. | PMID: 21840956 |
| Oral squamous cell carcinoma | Downregulation of CST2 may promote tumor invasion via increased cathepsin activity. | PMID: 23593055 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Salivary gland | 1234.5 | High |
| Trachea | 56.2 | Medium |
| Lung | 12.3 | Low |
| Kidney | 8.7 | Low |
| Liver | 2.1 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| A-431 (epidermoid carcinoma) | 15.3 | Moderate expression |
| HaCaT (keratinocyte) | 22.1 | Moderate expression |
| HPAF-II (pancreatic) | 1.2 | Low expression |
| SH-SY5Y (neuroblastoma) | 0.5 | Not detected |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | missense | <0.01% | Likely loss of start codon, predicted loss of function |
| c.124G>A (p.Gly42Ser) | missense | <0.01% | Unknown significance, rare population variant |
Mutation functional classification
Loss of Function (LOF)
Rare missense variants (e.g., p.Met1?) may abolish protein translation, leading to loss of protease inhibitory activity.
Gain of Function (GOF)
No gain-of-function mutations reported for CST2.
Dominant Negative (DN)
No dominant-negative mutations reported for CST2.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Cysteine protease inhibition (Reactome: R-HSA-8948216)
• Salivary secretion (KEGG: hsa04970)
Protein Summary
Cystatin SA is a 141-amino acid secreted protein (UniProt P09228) belonging to the cystatin family. It inhibits cysteine proteases such as cathepsins B, L, and S, and is abundant in saliva, where it contributes to oral homeostasis, antimicrobial defense, and regulation of inflammation. The protein contains a conserved cystatin domain and a signal peptide for secretion.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CST2 Knockout HEK293 Cell Line | EDJ-KQ4371 | Human | 1470 | Details Get a Quote |
| CST2 Knockout HeLa Cell Line | EDJ-KQ53016 | Human | 1470 | Details Get a Quote |
| CST2 Knockout A-549 Cell Line | EDJ-KQ61481 | Human | 1470 | Details Get a Quote |
| CST2 Knockout HCT 116 Cell Line | EDJ-KQ69977 | Human | 1470 | Details Get a Quote |
