Janus kinase 1 Janus homology 2 domain (JAK1 JH2)

The Janus kinase 1 (JAK1) Janus homology 2 (JH2) domain, also known as the pseudokinase domain, is a critical regulatory region of the JAK1 protein that lacks catalytic activity but controls the function of the adjacent JH1 kinase domain (UniProt P23458). Under normal physiological conditions, the JH2 domain exerts an autoinhibitory effect on the JH1 domain, preventing spontaneous activation of the JAK-STAT signaling pathway (PubMed: 24512202). Dysregulation or mutations in this domain can lead to constitutive signaling, contributing to the pathogenesis of inflammatory disorders, autoimmune diseases, and certain hematologic malignancies (PubMed: 25086043). While traditional JAK inhibitors target the ATP-binding site of the JH1 domain, the JH2 domain has become a focal point for the development of allosteric inhibitors that offer enhanced selectivity (PubMed: 30643204). By binding to the JH2 domain, these therapeutic agents stabilize the enzyme's inactive state, potentially reducing the side effects associated with the broader inhibition of other JAK family members (PubMed: 31431531). This targeting strategy is currently being explored in clinical and preclinical studies to provide more precise treatments for conditions such as rheumatoid arthritis and atopic dermatitis.

Other names

Janus kinase 1 pseudokinase domainJAK1 JH2 domainJanus homology 2 domain of JAK1

Allosteric inhibition by binding to the JH2 domain, which stabilizes the autoinhibitory interaction between the JH2 and JH1 domains, thereby preventing the catalytic JH1 domain from becoming active and signaling through the STAT pathway.