c-Jun NH2-terminal kinases (JNKs) are distant members of the MAP kinase family (1). JNK1 is activated by dual phosphorylation at a Thr-Pro-Tyr motif in response to ultraviolet (UV) light, and it functions to phosphorylate c-Jun at amino terminal serine regulatory sites, Ser-63 and Ser-73, resulting in transcriptional activation (2-5). Two additional JNK family members have been identified as JNK2 and JNK3 (3). JIP-1 (for JNK interacting protein-1) has been identified as a cytoplasmic inhibitor of JNK that retains JNK in the cytoplasm, thereby inhibiting JNK-regulated gene expression. Evidence suggests that JNK1 and JNK2 bind to JIP-1 with greater affinity than to ATF-2 and c-Jun, which are targets of the JNK signaling pathway. JIP-1 contains an amino terminal JNK binding domain and a carboxy terminal SH3 domain. ATF-2 and c-Jun also contain the JNK binding domain and are thought to compete with JIP-1 for JNK binding (6). Multiple splice variants if JIP-1, including JIP-1b, JIP-1c (also designated islet-brain 1 or IB-1), JIP-2a, JIP-2b and JIP-3, have been identified in brain (7).
Function:
The JNK-interacting protein (JIP) group of scaffold proteins selectively mediates JNK signaling by aggregating specific components of the MAPK cascade to form a functional JNK signaling module. JIP2 inhibits IL1 beta-induced apoptosis in insulin-secreting cells. May function as a regulator of vesicle transport, through interactions with the JNK-signaling components and motor proteins.
Subcellular Location:
Cytoplasm. Accumulates in cell surface projections.
Tissue Specificity:
Expressed mainly in the brain and pancreas, including insulin-secreting cells. In the nervous system, more abundantly expressed in the cerebellum, pituitary gland, occipital lobe and the amygdala. Also expressed in fetal brain. Very low levels found in uterus, ovary, prostate, colon, testis, adrenal gland, thyroid gland and salivary gland.
Similarity:
Belongs to the JIP scaffold family.
Contains 1 PID domain.
Contains 1 SH3 domain.
SWISS:
Q13387
Gene ID:
23542
Database links:
Entrez Gene: 23542 Human
Entrez Gene: 60597 Mouse
Entrez Gene: 315220 Rat
Omim: 607755 Human
SwissProt: Q13387 Human
SwissProt: Q9ERE9 Mouse
Unigene: 55836 Human
Unigene: 173337 Mouse
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