The Fos and Jun families of eukaryotic transcription factors heterodimerize to form complexes capable of binding 5'-TGAGTCA-3' DNA elements. We have determined the X-ray crystal structure of a heterodimer of the bZIP regions of c-Fos and c-Jun bound to DNA. Both subunits form continuous alpha-helices. The carboxy-terminal regions form an asymmetric coiled-coil, and the amino-terminal regions make base-specific contacts with DNA in the major groove. Comparison of the two crystallographically distinct protein-DNA complexes show that the coiled-coil is flexibly joined to the basic regions and that the Fos-Jun heterodimer does not recognize the asymmetric 5'-TGAGTCA-3' recognition element in a unique orientation. There is an extensive network of electrostatic interactions between subunits within the coiled-coil, consistent with proposals that these interactions determine preferential formation of the heterodimer over either of the homodimers.

Whole-transcriptome sequencing of four GCTs identified a single, recurrent somatic mutation (402C-->G) in FOXL2 that was present in almost all morphologically identified adult-type GCTs. Mutant FOXL2 is a potential driver in the pathogenesis of adult-type GCTs.

The nuclear factor of activated T cells (NFAT) and the AP-1 heterodimer, Fos-Jun, cooperatively bind a composite DNA site and synergistically activate the expression of many immune-response genes. A 2.7-A-resolution crystal structure of the DNA-binding domains of NFAT, Fos and Jun, in a quaternary complex with a DNA fragment containing the distal antigen-receptor response element from the interleukin-2 gene promoter, shows an extended interface between NFAT and AP-1, facilitated by the bending of Fos and DNA. The tight association of the three proteins on DNA creates a continuous groove for the recognition of 15 base pairs.