p-JAK3 (Tyr 980) Antibody: sc-16567

JAK3 Background Information
Several members of the Janus family of protein tyrosine kinases have been described (1–4). These include Tyk 2 (1), JAK1 (2) and JAK2 (3,4), each of which is involved in coupling ligand binding of cytokine receptors to tyrosine phosphorylation. Subsequent to activation, these kinases function to activate various members of the Stat family of transcription factors by phosphorylation on critical tyrosine regulatory sites. The most recent member of the Janus family of transcription factors, JAK3 (also designated L-JAK), is activated in response to IL-3 and IL-4 in T cells and myeloid cells (5–7). JAK3 activation requires the serine-rich membrane-proximal region of the IL-2 receptor b-chain, but does not require the acidic domain that is required for association and activation of Src family kinases (7). Expression of JAK3 is restricted to NK and T cells, whereas the other members of the Janus family of tyrosine protein kinases are much more widely expressed (6). JAK3 is autophosphorylated on multiple sites including Tyrosines 980 and 981 (8). However, optimal phosphorylation of JAK3 on other sites is dependent on Tyrosine 980 phosphorylation (8). Tyrosine 980 positively regulates JAK3 kinase activity whereas Tyrosine 981 negatively regulates JAK3 kinase activity (8).