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The gene on chromosome 19p13.1 that encodes Janus kinase 3 (OMIM:600173, UniProtKB:P52333), a member of the Janus kinase–JAK family of non-receptor tyrosine kinases which are involved in various processes such as cell growth, development, or differentiation. It mediates signaling events in innate and adaptive immunity, plays key roles in haematopoiesis during T-cells development and in signal transduction by associating with type I receptors sharing the common subunit gamma such as IL2R, IL4R, IL7R, IL9R, IL15R and IL21R. Following ligand binding to cell surface receptors, JAK3phosphorylates specific tyrosine residues on the cytoplasmic tails of the receptor, creating docking sites for STATs proteins.
Molecular pathology Defects of JAK3 cause severe combined immunodeficiency disease—autosomal recessive—T cell negative—B cell positive—NK cell negative (OMIM:600802).
Synonyms Leukocyte Janus kinase, EC 22.214.171.124, JAKL, tyrosine-protein kinase JAK3