Mitogen-activated protein (MAP) kinase, JNK (IPR008351)
Short name: MAPK_JNK
Protein phosphorylation, which plays a key role in most cellular activities, is a reversible process mediated by protein kinases and phosphoprotein phosphatases. Protein kinases catalyse the transfer of the gamma phosphate from nucleotide triphosphates (often ATP) to one or more amino acid residues in a protein substrate side chain, resulting in a conformational change affecting protein function. Phosphoprotein phosphatases catalyse the reverse process. Protein kinases fall into three broad classes, characterised with respect to substrate specificity [PMID: 3291115]:
- Serine/threonine-protein kinases
- Tyrosine-protein kinases
- Dual specificity protein kinases (e.g. MEK - phosphorylates both Thr and Tyr on target proteins)
Protein kinase function is evolutionarily conserved from Escherichia coli to human [PMID: 12471243]. Protein kinases play a role in a multitude of cellular processes, including division, proliferation, apoptosis, and differentiation [PMID: 12368087]. Phosphorylation usually results in a functional change of the target protein by changing enzyme activity, cellular location, or association with other proteins. The catalytic subunits of protein kinases are highly conserved, and several structures have been solved [PMID: 15078142], leading to large screens to develop kinase-specific inhibitors for the treatments of a number of diseases [PMID: 15320712].
MAP (Mitogen Activated Protein) kinases participate in kinase cascades, whereby at least 3 protein kinases act in series, culminating in activation of MAP kinase [PMID: 10487205]. MAP kinases are activated by dual phosphorylation on both tyrosine and threonine residues of a conserved TXY motif.
JNK (Jun N-terminal Kinase), also known as Stress Activated Protein Kinase (SAPK), belongs to the family of MAP kinases [PMID: 11790549]. JNKs are activated by cytokines, certain ligands for GPCRs, agents that interfere with DNA and protein synthesis, and to some extent by growth factors, serum and transforming agents. Three genes have been identified in humans: JNK1, JNK2 and JNK3. Knockouts of these genes have revealed that JNK1 and/or JNK2 must have a role in both apoptosis and the immune response.
- PR01772 (JNKMAPKINASE)