AP-1

Definition

Activating protein-1 (AP-1) is a transcription factor usually consisting of a member of the Jun family and a member of the Fos or ATF family of proto-oncogenes. AP-1 is activated in response to cytokines, growth factors, and stress factors during cell differentiation, tumor formation, or mitogenic response.

Characteristics

Much of our present knowledge about transcription factors comes from the discovery and study of the activating protein-1 (AP-1) family. AP-1 (and the transcription factor NFκB) has served to detect one of the decisive DNA binding motifs required for gene regulation by a variety of extracellular signals including growth factors, cytokines, tumor promoters, such as the phorbol ester TPA (12-O-tetradecanoyl-phorbol-13-acetate), and carcinogens, for example, UV irradiation and other DNA damaging agents. One of its members, the heterodimer Fos-Jun, was found in the mid-1980s as a protein complex containing the viral oncogeneproduct Fos without a clue of its...