JAK3 is a tyrosine kinase that activates via cytokine receptors (IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21). JAK3 also autophosphorylates in the presence of ATP; examples of that can be seen in the data below. JAK3 phosphorylates and activates STATs that induce the expression of genes in the cell nucleus.
Recent research has shown that JAK3 activation is common in many different cancers and that JAK3 autophosphorylation could be a rate-limiting step. JAK3 mutations have been identified in different forms of leukemia and lymphoma. Inhibiting JAK3 or JAK1 could provide a potential treatment for these cancers.
Because it is expressed only in hematopoietic cells (which should help to limit off-target effects), JAK3 is also being vetted for autoimmune diseases like rheumatoid arthritis. Tofacitinib, a JAK1 and JAK3 inhibitor, is currently marketed by Pfizer. New specific JAK3 inhibitors could help limit the current off-target effects of the drug.
The Transcreener ADP2 JAK3 Assay is an excellent tool for researchers examining the therapeutic effects of JAK3.