InterPro: IPR000837 Fos transforming protein

Both the cellular and viral forms of the fos oncogene encode a phosphoprotein that is located in the nucleus of cells, and forms a noncovalent complex with several other proteins. A leucine zipper holds the dimer together. The dimer is associated with chromatin and demonstrates specific and non-specific DNA-binding properties [1], the DNA being bound by a highly basic area in the protein sequence immediately preceding the zipper domain. Expression of the fos gene is stimulated by mitogens, suggesting that the gene product is involved in cell growth [2], and may act as a nuclear signal in a more general sense. The 'leucine zipper' is a structure that is believed to mediate the function of several eukaryotic gene regulatory proteins. The zipper consists of a periodic repetition of leucine residues at every seventh position, and regions containing them appear to span 8 turns of alpha-helix. The leucine side chains that extend from one helix interact with those from a similar helix, hence facilitating dimerisation in the form of a coiled-coil. Leucine zippers are present in many gene regulatory proteins, including the CREB proteins, Jun/AP1 transcription factors, fos oncogene and fos-related proteins, C-myc, L-myc and N-myc oncogenes, and so on.