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Catalytic domain of the dual-specificity Protein Kinase, Mitogen-activated protein Kinase Kinase 7 PKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine (ST) or tyrosine residues on protein substrates. MKK7 is a dual-specificity PK that phosphorylates and activates its downstream target, c-Jun N-terminal kinase (JNK), on specific threonine and tyrosine residues. Although MKK7 is capable of dual phosphorylation, it prefers to phosphorylate the threonine residue of JNK. Thus, optimal activation of JNK requires both MKK4 and MKK7. MKK7 is primarily activated by cytokines. MKK7 is essential for liver formation during embryogenesis. It plays roles in G2/M cell cycle arrest and cell growth. In addition, it is involved in the control of programmed cell death, which is crucial in oncogenesis, cancer chemoresistance, and antagonism to TNFalpha-induced killing, through its inhibition by Gadd45beta and the subsequent suppression of the JNK cascade. The MKK7 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.
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