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pubmed:abstractText |
The nuclear function of the c-Abl tyrosine kinase is not well understood. In order to identify nuclear substrates of Abl, we constructed a constitutively active and nuclear form of the protein. We found that active nuclear Abl efficiently phosphorylate c-Jun, a transcription factor not previously known to be tyrosine phosphorylated. After phosphorylation of c-Jun by Abl on Tyr170, both proteins interacted via the SH2 domain of Abl. Surprisingly, elevated levels of c-Jun activated nuclear Abl, resulting in activation of the JNK serine/threonine kinase. This phosphorylation circuit generates nuclear tyrosine phosphorylation and represents a reversal of previously known signalling models.
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