CSK (C-Terminal Src Kinase)
A key negative regulator of Src family tyrosine kinases, involved in cell growth, differentiation, and immune signaling.
Gene Information Card
| Symbol | CSK |
|---|---|
| Full Name | C-terminal Src kinase |
| Gene Type | protein-coding |
| Chromosomal Location | 15q24.1 |
| NCBI Gene ID | 1445 ncbi.nlm.nih.gov/gene/1445 |
| Ensembl ID | ENSG00000103653 |
| UniProt ID | P41240 |
| OMIM ID | 190090 |
| HGNC ID | 2444 |
| Aliases | CSK, C-Src kinase, CSK tyrosine kinase |
Description
The CSK gene encodes C-terminal Src kinase, a cytoplasmic tyrosine kinase that negatively regulates Src family kinases (SFKs) by phosphorylating their C-terminal inhibitory tyrosine residue. CSK plays a critical role in controlling cell proliferation, adhesion, migration, and immune receptor signaling. Dysregulation of CSK is implicated in various cancers and immune disorders.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Hepatocellular carcinoma | Reduced CSK expression leads to increased SFK activity, promoting cell proliferation and invasion. | PMID: 23455478 |
| Colorectal cancer | CSK downregulation correlates with Src activation and poor prognosis. | PMID: 17157791 |
| Breast cancer | Loss of CSK expression enhances Src-dependent signaling and metastasis. | PMID: 18413744 |
| T-cell immunodeficiency | Mutations in CSK impair T-cell receptor signaling and immune response. | PMID: 25642768 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Lymph node | 12.5 | Medium |
| Spleen | 11.8 | Medium |
| Bone marrow | 10.2 | Medium |
| Brain | 8.5 | Low |
| Liver | 7.3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| K-562 (leukemia) | 14.2 | High expression |
| HeLa (cervical) | 9.8 | Moderate |
| A549 (lung) | 8.1 | Moderate |
| MCF7 (breast) | 6.5 | Low |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.791G>A (p.Arg264His) | Missense | <0.01% | Reduced kinase activity; associated with T-cell immunodeficiency. |
| c.1123C>T (p.Arg375*) | Nonsense | <0.01% | Loss of function; truncation of protein. |
| c.1A>G (p.Met1Val) | Start loss | <0.01% | Loss of translation initiation; likely loss of function. |
Mutation functional classification
Loss of Function (LOF)
Missense and nonsense mutations that reduce or abolish CSK kinase activity, leading to increased SFK signaling.
Gain of Function (GOF)
No well-characterized gain-of-function mutations reported in CSK.
Dominant Negative (DN)
No dominant-negative mutations described for CSK.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Regulation of Src family kinases (Reactome: R-HSA-8848021)
• Signaling by Src-family kinases (Reactome: R-HSA-177929)
• T-cell receptor signaling pathway (KEGG: hsa04660)
• Fc gamma R-mediated phagocytosis (KEGG: hsa04666)
Protein Summary
CSK is a 50 kDa cytoplasmic tyrosine kinase composed of an N-terminal SH2 domain, a central SH3 domain, and a C-terminal kinase domain. It specifically phosphorylates the C-terminal tyrosine (Tyr530 in Src) of Src family kinases, inducing an intramolecular inhibitory conformation. CSK is ubiquitously expressed but enriched in hematopoietic tissues. Its activity is essential for maintaining low basal SFK activity and regulating immune receptor signaling.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CSK Knockout HEK293 Cell Line | EDJ-KQ4363 | Human | 1445 | Details Get a Quote |
| CSKMT Knockout HEK293 Cell Line | EDJ-KQ13016 | Human | 751071 | Details Get a Quote |
| CSK Knockout A-549 Cell Line | EDJ-KQ25589 | Human | 1445 | Details Get a Quote |
| CSK Knockout HCT 116 Cell Line | EDJ-KQ26872 | Human | 1445 | Details Get a Quote |
| CSK Knockout HeLa Cell Line | EDJ-KQ26873 | Human | 1445 | Details Get a Quote |
| CSKMT Knockout A-549 Cell Line | EDJ-KQ42276 | Human | 751071 | Details Get a Quote |
| CSKMT Knockout HCT 116 Cell Line | EDJ-KQ42277 | Human | 751071 | Details Get a Quote |
| CSKMT Knockout HeLa Cell Line | EDJ-KQ42278 | Human | 751071 | Details Get a Quote |
