Janus kinase JH1 catalytic domain (JAK JH1 domain)

The **JH1 catalytic domain** is the C-terminal, highly conserved kinase domain present in all Janus kinases (JAK1, JAK2, JAK3, TYK2)[1][3][4][6]. It features the classical protein kinase fold, including an ATP-binding site and critical regulatory motifs (such as the DFG motif)[3]. The domain carries out the phosphorylation of tyrosine residues on nearby cytokine receptors, thereby initiating the activation of STAT transcription factors and downstream immune signaling. This activity is tightly regulated by an adjacent pseudokinase (JH2) domain. Drugs targeting the JH1 domain are clinically important for treating autoimmune diseases and myeloproliferative conditions[3][4][6]. Key points: - The JH1 catalytic domain is not a unique molecule but a conserved region found in all four main JAK family members. - Most clinical/research targeting is directed against specific isoforms (e.g., JAK1, JAK2) rather than “JH1 domain” in isolation. - It is a validated therapeutic enzyme target, particularly in immunology and oncology. If a more specific JAK isoform (e.g., "Janus kinase 1") is intended, a different canonical name and more tailored information would be required[1][4].

Other names

JAK kinase domainJAK tyrosine kinase domainJH1 domainJAK catalytic domain

ATP-competitive inhibition of the JH1 kinase domain Prevention of tyrosine phosphorylation of STATs and subsequent gene transcription