JNK13

JNK13 is not a standard designation in the current mammalian mitogen-activated protein kinase (MAPK) literature. The JNK subfamily traditionally comprises three kinases: JNK1 (MAPK8), JNK2 (MAPK9), and JNK3 (MAPK10). Major gene and protein databases (such as HGNC and UniProt) do not list a widely recognized entry for JNK13, suggesting that if the term is encountered it may reflect a misnaming, a species-specific nomenclature, or an informal reference rather than a validated, distinct kinase.

In the canonical JNK signaling pathway, JNKs are serine/threonine kinases activated by a tiered cascade. Upstream MAP3Ks activate MAP2Ks (MKK4 and MKK7), which in turn phosphorylate and activate JNKs. Activated JNKs phosphorylate a range of substrates, including the transcription factor c-Jun and other members of the AP-1 complex, as well as ATF2 and various scaffold proteins. Through these targets, JNK signaling influences gene expression, apoptosis, differentiation, inflammatory responses, and neuronal plasticity. Among the JNKs, JNK3 is relatively enriched in brain tissue, whereas JNK1 and JNK2 are more widely expressed across tissues.

Clinical and research relevance centers on dysregulation of JNK signaling in conditions such as neurodegenerative diseases, cancer, and metabolic disorders. Pharmacological inhibitors targeting JNK activity have been explored in preclinical and clinical studies, including pan-JNK inhibitors and more selective compounds, though no JNK13-specific agent exists in standard pharmacological catalogs.

If a source references JNK13, it should be cross-checked for possible misnaming or a context-specific, nonstandard usage to confirm whether it truly denotes a distinct kinase or another protein.