The ternary complex factor Net contains two distinct elements that mediatedifferent responses to MAP kinase signalling cascades

The ternary complex factors (TCFs), Elk-1, Sap-1a and Net, are key integrat ors of the transcriptional response to different signalling pathways. Class ically, three MAP kinase pathways, involving ERK, JNK, and p38, transduce v arious extracellular stimuli to the nucleus. Net is a repressor that is con verted into an activator by Ras/ERK signalling. Net is also exported from t he nucleus in response to stress stimuli transduced through the JNK pathway , leading to relief from repression. Here we show that ERK and p38 bind to the D box and that binding is required for phosphorylation of the adjacent C-terminally located C-domain, The D box as web as the phosphorylation site s in the C-domain (the DC element) are required for transcription activatio n by Pas. On the other hand, JNK binds to the J box in the middle of the pr otein, and binding is required for phosphorylation of the adjacent EXport m otif. Both the binding and phosphorylation sites (the JEX element) are impo rtant for Net export. In conclusion, specific targeting of Net by MAP kinas e pathways involves two different docking sites and phosphorylation of two different domains. These two elements, DC and JEX, mediate two distinct fun ctional responses.