Non-Receptor Tyrosine Kinase (PTKS)-enzyme

Non-receptor tyrosine kinases, also known as cytoplasmic tyrosine kinases, are a subfamily of tyrosine kinases, which are responsible for transferring a phosphate group to a tyrosine residue in proteins. Unlike the other group of tyrosine kinases, the receptor tyrosine kinases, the non-receptor tyrosine kinases lack transmembrane domain and are located inside of the cells. Based on sequence similarities of kinase domains, non-receptor tyrosine kinases are further classified into 10 subfamilies, including ABL, ACK, CSK, FAK, FES, FRK, JAK, SRC, TEC and SYK. In addition to the kinase domain, non-receptor tyrosine kinases also have several signaling or protein-protein interaction domains, such as SH2 and PH domains.

Based on sequence similarities of kinase domains, non-receptor tyrosine kinases are further classified into 10 subfamilies, including ABL, ACK, CSK, FAK, FES, FRK, JAK, SRC, TEC and SYK.

Activity of non-receptor tyrosine kinase

The enzymatic activities of both receptor tyrosine kinases and non-receptor tyrosine kinases are tightly controlled by cells. For example, nonproliferating cells have less phosphorylated tyrosine residues in proteins. Compared to the receptor tyrosine kinase, the activation mechanisms of non-receptor tyrosine kinases are more complicated, which involve heterogeneous protein-protein interaction to enable transphosphorylation. Due to the presence of cellular inhibition proteins and lipids and through intramolecular autoinhibition, non-receptor tyrosine kinases are maintained in an inactivated state. Through intracellular activation signals, non-receptor tyrosine kinases are recruited to transmembrane receptors and phosphorylated by other kinases.

Function of non-receptor tyrosine kinase

Non-receptor tyrosine kinases regulate multiple cellular processes, such as proliferation, differentiation and adhesion, and are also critical to regulating immune systems. Furthermore, studies suggest that non-receptor tyrosine kinases are targets for cancer therapies. For example, Src, a non-receptor tyrosine kinase, is the first proto-oncogene, which is resulted in two Nobel Prize to date.

JAK kinase
JAK1 JAK2 JAK3
TYK2    
FAK kinase
PTK2/FAK1
TEC kinase
BTK/Bruton Tyrosine Kinase BMX ITK/ITK Kinase
TEC    
SRC kinase
SRC YES1/c-Yes FYN
Lck LYN HCK
BLK/BLK Kinase FRK PTK6/Brk
ABL kinase
c-Abl/ABL1 ARG1/Arginase 1 ARG2/Arginase II
SYK kinase
Syk ZAP/ZAP-70  
FRK kinase
FRK/RAK PTK6/Brk  
FES kinase
FES/Feline sarcoma oncogene
CSK kinase
CSK/C-Src Kinase MATK/CHK  
ACK kinase
ACK1/TNK2
Enzymes | Proteases | Kinases
Proteases products center
kinase products center
Protein Kinase Introduction
Protein kinase classified by catalytic domains
Protein kinase classified by substrates+
- Tyrosine Kinase
- tyrosine-kinase like group of kinases
- Receptor Tyrosine Kinase (RTKs)
- Non-Receptor Tyrosine Kinase (PTKS)
- Serine Threonine Kinase
- Histidine Kinase-HK
Protein Kinase Inhibitor
Dual specificity kinase
Intracellular Kinases
Protein kinase related to signaling pathway
Protein Kinase in the Akt Pathway
Protein Kinase in Apoptosis Regulation
Lipid Kinase
Other Enzymes products center