What is the Difference Between JAK1 JAK2 and JAK3?
🆚 Go to Comparative Table 🆚The Janus kinases (JAKs) are a family of intracellular non-receptor protein tyrosine kinases, which play a crucial role in signal transduction initiated by a wide range of membrane receptors. The four main members of the JAK family are JAK1, JAK2, JAK3, and TYK2. Each JAK has a unique subcellular expression pattern and is involved in different signaling pathways:
- JAK1: Essential for signaling of certain type I and type II cytokines. It is involved in the signaling of various receptors, such as type I and II cytokine receptor family, GM-CSF receptor family, gp130 receptor family, and single-chain receptors.
- JAK2: Essential for signaling of type II cytokine receptors, gp130 receptor family, and single-chain receptors. Genetic inactivation of JAK2 in mice is lethal, as the embryo dies around 12 days of gestation.
- JAK3: Expressed primarily in hematopoietic cells and is essential for signaling of type I receptors that use the common gamma chain (γc). JAK3 is involved in the immune cell signaling and development of immune cells.
The key difference between JAK1, JAK2, and JAK3 lies in their specific functions and subcellular expression patterns. While JAK1 is essential for signaling of certain type I and type II cytokines, JAK2 is involved in the signaling of type II cytokine receptors and single-chain receptors. JAK3, on the other hand, is essential for signaling of type I receptors that use the common gamma chain (γc).
Comparative Table: JAK1 JAK2 vs JAK3
The Janus family kinases (Jaks) are a subgroup of non-receptor protein tyrosine kinases, with four main members: JAK1, JAK2, JAK3, and TYK2. Here is a table highlighting the differences between JAK1, JAK2, and JAK3:
| JAK Family Member | Chromosomal Location | Associated Receptors | Main Functions |
|---|---|---|---|
| JAK1 | 1p31.3 | Various | Essential for IFN-induced STAT phosphorylation. Involved in immune function and homeostasis. |
| JAK2 | 9p24 | Various | Critical for erythropoiesis, myelopoiesis, and platelet production. Involved in immune function and homeostasis. |
| JAK3 | 19p13.1 | γc chain (IL-2, IL-4, IL-7, IL-9, IL-15, IL-21 receptors) | Restricted to the common ɣ chain-containing receptors and plays a role in lymphocyte proliferation and homeostasis. Severely reduced numbers of bone marrow cells and B cell lymphopenia in deficient mice. |
JAK1 and JAK2 are widely expressed and play essential roles in immune function and homeostasis, while JAK3 is more restricted in its expression and function. JAK3 is mainly involved in the function of lymphocytes and is associated with the γc chain, which is a subunit of receptors for various cytokines.
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