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Catalytic domain of the dual-specificity Protein Kinase, Mitogen-activated protein Kinase Kinase 4 PKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine (ST) or tyrosine residues on protein substrates. 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. The MKK4 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.",