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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 โŸถ called tyrosine kinase-associated receptor.

  • Kinases that associate with these receptors are:

  • JAK (Janus family)

  • Src family

  • Example: Receptors for:

  • Some cytokines e.g. IL-2 to IL-6

  • GM-CSF

  • Erythropoietin

  • Growth hormone

  • Prolactin

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.


JAK-STAT Pathway

  • Under resting state: Receptors exist as monomers.

Binding of the ligand with the receptor

โ†“

Receptors associate to form a dimer

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Dimerization increases affinity for JAK

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JAKs associate with receptor

โ†“

JAK get activated

โ†“

JAKs phosphorylate tyrosine residues on each other and on receptor molecules

โ†“

Formation of phosphotyrosine residues

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STAT (Signal Transducers and Activators of Transcription) binds with phosphotyrosine residues

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JAK phosphorylates STAT

โ†“

STATs dissociate from the receptor and form a dimer

โ†“

Dimer goes to the nucleus

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Regulates gene transcription

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Response

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โ–ถ๏ธ Nuclear Receptors and Their Signaling Pathway
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