Behind the Fos and Jun leucine zipper.

The production of the nuclear oncoproteins Fos and Jun is rapidly induced in response to extracellular signals. In the nucleus, the two proteins combine to form a tight complex via leucine zipper domains. The resulting Fos-Jun heterodimer can bind to the TPA-responsive element (TRE) by way of a novel, highly basic motif and can activate the transcription of TPA-responsive genes. The existence of several Fos- and Jun-related proteins with dimerization and DNA binding properties similar to Fos and Jun suggests that these two oncoproteins may be part of a network of related but functionally distinct transcription factors.