JAK3 Protein, Human (Active, sf9, GST)

JAK3 is a non-receptor tyrosine kinase involved in various processes such as cell growth, development, or differentiation. It mediates essential signaling events in both innate and adaptive immunity and plays a crucial role in hematopoiesis during T-cell development. In the cytoplasm, JAK3 plays a pivotal role in signal transduction by associating with type I receptors that share the common γ subunit, such as IL2R, IL4R, IL7R, IL9R, IL15R, and IL21R. Following ligand binding to cell surface receptors, JAK3 phosphorylates specific tyrosine residues on the cytoplasmic tails of the receptor, creating docking sites for STATs proteins. It then phosphorylates the recruited STATs proteins, which subsequently form homodimers or heterodimers and translocate to the nucleus to activate gene transcription. For example, upon IL2 binding to IL2R, JAK1 and JAK3 bind to the IL2R β (IL2RB) and γ (IL2RG) subunits, inducing tyrosine phosphorylation of both receptor subunits. STAT5A and STAT5B are then recruited, phosphorylated, and activated by JAK1 and JAK3. The activated, dimerized STAT5 translocates to the nucleus to promote transcription of specific target genes in a cytokine-specific manner.