JAK2 protein description
JAK2 protein (Janus kinase 2, Tyrosine-protein kinase JAK2) is a non-receptor tyrosine kinase and member of the Janus kinase family and has been implicated in signaling by members of the type II cytokine receptor family, the GM-CSF receptor family (IL-3R, IL-5R and GM-CSF-R), the gp130 receptor family (e.g., IL-6R), and the single chain receptors (Epo-R, Tpo-R, GH-R, PRL-R). Following the ligand-binding, JAK2 protein gets activated via transphosphorylation of receptor JAK membrane molecules. Once activated, these proteins phosphorylate substrates on tyrosine which provides docking sites to recruit downstream signaling proteins such as STAT family of proteins. The latter are phosphorylated and form a homodimer or a heterodimer and translocate to the nucleus where they activate gene transcription. In addition, JAK2 protein also mediates angiotensin-2-induced ARHGEF1 phosphorylation. JAK2 kinase lays is involved in cell cycle by phosphorylating CDKN1B protein. Other interactions involve its cooperation with TEC vis reciprocal phosphorylation to mediate cytokine-driven activation of FOS transcription. In the nucleus, JAK2 protein is essential for the phosphorylation of ‘Tyr-41’ of histone H3 (H3Y41ph) which promotes exclusion of CBX5 (HP1 alpha) from chromatin.