Tyrosine Kinase Associated Receptor and JAK-STAT Pathway
Tyrosine Kinase Associated Receptor
The receptor itself has no enzymatic activity.
Associate with a separate molecule that has tyrosine kinase activity ⟶ called tyrosine kinase-associated receptor.
Kinases that associate with these receptors are:
JAK (Janus family)
Example: Receptors for:
Some cytokines e.g. IL-2 to IL-6
Tyrosine Kinase Associated Receptor vs Receptor Tyrosine Kinase
Receptor Tyrosine Kinase is a single molecule that works as a receptor as well as tyrosine kinase.
In Tyrosine kinase-associated receptor, the receptor and enzyme are two separate molecules that associate with each other.
Despite this difference, they both work in a similar manner.
Under resting state: Receptors exist as monomers.
Binding of the ligand with the receptor
Receptors associate to form a dimer
Dimerization increases affinity for JAK
JAKs associate with receptor
JAK get activated
JAKs phosphorylate tyrosine residues on each other and on receptor molecules
Formation of phosphotyrosine residues
STAT (Signal Transducers and Activators of Transcription) binds with phosphotyrosine residues
JAK phosphorylates STAT
STATs dissociate from the receptor and form a dimer
Dimer goes to the nucleus
Regulates gene transcription