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Catalytic domain of the Serine/Threonine Kinase, Mixed Lineage Kinase 3 STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. MLK3 is a mitogen-activated protein kinase kinase kinases (MAP3K, MKKK, MAPKKK), which phosphorylates and activates MAPK kinases (MAPKKs or MKKs or MAP2Ks), which in turn phosphorylate and activate MAPKs during signaling cascades that are important in mediating cellular responses to extracellular signals. MLK3 activates multiple MAPK pathways and plays a role in apoptosis, proliferation, migration, and differentiation, depending on the cellular context. It is highly expressed in breast cancer cells and its signaling through c-Jun N-terminal kinase has been implicated in the migration, invasion, and malignancy of cancer cells. MLK3 also functions as a negative regulator of Inhibitor of Nuclear Factor-KappaB Kinase (IKK) and consequently, it also impacts inflammation and immunity. Mammals have four MLKs, mostly conserved in vertebrates, which contain an SH3 domain, a catalytic kinase domain, a leucine zipper, a proline-rich region, and a CRIB domain that mediates binding to GTP-bound Cdc42 and Rac. MLKs play roles in immunity and inflammation, as well as in cell death, proliferation, and cell cycle regulation.The MLK3 subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",