1. Signaling Pathways
  2. Protein Tyrosine Kinase/RTK
  3. Non-receptor Tyrosine Kinase

Non-receptor Tyrosine Kinase

Synonyms: NRTK

Non-receptor tyrosine kinases (NRTKs) lack both an extracellular and transmembrane domain, and most reside in the cytoplasm of cells, including in immune cells. In addition to their kinase domain, all nine families of NRTKs share homologous Src homology 2 (SH2) and 3 (SH3) protein-protein binding domains. The SH2 domains are responsible for binding phosphotyrosines on proteins while SH3 domains bind to proline-rich regions in proteins. Both of these domains function in signal transduction by interacting with their target proteins and are thought to negatively regulate kinase activity.