cd06616: PKc_MKK4 (this model, PSSM-Id:132947 is obsolete and has been replaced by 270790)
Catalytic domain of the dual-specificity Protein Kinase, MAP kinase kinase 4
Protein kinases (PKs), MAP kinase kinase 4 (MKK4) subfamily, catalytic (c) domain. PKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine or tyrosine residues on protein substrates. The MKK4 subfamily is part of a larger superfamily that includes the catalytic domains of other protein serine/threonine kinases, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. The mitogen-activated protein (MAP) kinase signaling pathways are important mediators of cellular responses to extracellular signals. The pathways involve a triple kinase core cascade comprising of the MAP kinase (MAPK), which is phosphorylated and activated by a MAPK kinase (MAPKK or MKK), which itself is phosphorylated and activated by a MAPK kinase kinase (MAPKKK or MKKK). MKK4 is a dual-specificity PK that phosphorylates and activates the downstream targets, c-Jun N-terminal kinase (JNK) and p38 MAPK, on specific threonine and tyrosine residues. JNK and p38 are collectively known as stress-activated MAPKs, as they are activated in response to a variety of environmental stresses and pro-inflammatory cytokines. Their activation is associated with the induction of cell death. Mice deficient in MKK4 die during embryogenesis and display anemia, severe liver hemorrhage, and abnormal hepatogenesis. MKK4 may also play roles in the immune system and in cardiac hypertrophy. It plays a major role in cancer as a tumor and metastasis suppressor. Under certain conditions, MKK4 is pro-oncogenic.